Sous-famille Laganinae  Agassiz, 1873

description succinte : Laganidae avec structure d'assules simples sur les ambulacres. Plaques basicoronales en forme d'étoile, les plaques ambulacraires étant plus longues.

Genre Jacksonaster  Lambert & Thiery,1914

Essai de nomenclature raisonnée des échinides, p.313

Espèce type  Laganum depressum Agassiz,1841 (désignation subséquente de Lambert & Thiery,1914, Essai de nomenclature raisonnées des échinides, p.313)

Monographies d'échinodermes, des Scutelles, p.110

Extension stratigraphique (bibliographique, non vérifiée) : Miocène - Actuel

Jacksonaster depressum Agassiz,1841, Pléistocène, Egypte, 53 mm

Jacksonaster depressum Agassiz,1841, Pléistocène, Jordanie, 46 mm

Jacksonaster depressum Agassiz,1841, Plio - Pléistocène, Egypte, 23 et 16 mm

Genre Peronella  Gray,1855

Catalogue of the recent echinida of sea eggs in the collection of the British Museum, p.13

Espèce type  Laganum peronii Agassiz,1841 (désignation originale)

Extension stratigraphique (bibliographique, non vérifiée) : Pléistocène - Actuel

Syn.

• Lambertiella Checchia Rispoli, 1917, p.57 ; espèce type : Lambertiella pulchra Checchia Rispoli, 1917

Peronella orbicularis (Leske,1778), Pléistocène, Dampier Limestone, Australie de l'Ouest, 20 mm

Genre Rumphia  Desor,1858

synopsis des échinides fossiles, p.229

Espèce type  Laganum rostratum Agassiz,1841 (désignation originale)

Extension stratigraphique (bibliographique, non vérifiée) : Miocène - Actuel

Syn.

• Polyaster Michelin, 1859, non Gray, 1840

• Peronellites Hayasaka & Morishita, 1947, p.101 ; espèce type : Peronellites ovalis Hayasaka & Morishita,1947

Rumphia ova (Mc Namara,1996), Pliocène supérieur, Australie de l'Ouest, 30 mm

Rumphia ricta (Gregory,1892)

Species, Laganum decagonale, Lesson. Var. rictum, n. var. Pl. XII. Fig. 1.

     Diagnosis (of the Variety).

     Form : elongated elliptic ; the posterior end is longer and narrower than the anterior ; the anterior end is semicircular ; the sides taper backward. The base is flat ; the margins are tumid, and are separated from the slightly conical apex by either a flat platform or a slight broad depression.

     Ambulacra : Petals extend two-thirds of the distance from the apex to the ambitus ; the lateral pairs are equal in length ; the anterior ambulacrum is the longest. The petals are sharply closed below ; the width of the pore area expands rather gradually to the distal end of the petal, then is there closed somewhat abrubtly. The interporiferous areas are large, and taper slightly to the blunt distal end.

     Apical system : at the apex of the test. The madreporite is raised, large, and central. There are four large genital pores. Of the radial (ocular) pores the right antero-lateral is very large ; those of the right postero-lateral and left antero-lateral ambulacra are small ; the left postero-lateral pore is not developed.

     Peristome : mouth somewhat pentagonal ; large ; the width is half as much again as the length. It is situated before the centre. There are no interradial actinal furrows.

     Periproct : the anus is large and almost circular ; it is close to the margin.

     Distribution. - Cainozoic. Shark's Bay, West Australia.

Collected by Harry Page Woodward, Esq., F.G.S.

     Affinities and Differences. - The specimen on which this species is founded is unquestionably a very close ally of Laganum decagonale, Less., though as to whether it should be regarded as a variety or a distinct species, I do not care to express an opinion on a single specimen. It differs from that

species by the elliptical and somewhat pentagonal shape of the mouth, and the absence of the five interradial furrows which radiate from the mouth. The British Museum contains a large series of specimens of that species, but the circular form of the mouth is constant ; the actinal depressions do vary in debree of development, but I have not seen one in which it is not quite distinct. These two characters may not improbably be of specific value.

     The shape of the test differs from the normal decagonal form ; but some specimens of the species have a form identical with the fossil.

     Herklots figured a specimen from the Java Tertiaries as Scutella decagona, n. sp., Martin referred this to Peronella decagonalis, Ag., and included L. angulosum, Herklots, as a synonym ; but as Herklots neither figured nor described the actinal side, a certain amount of doubt must remain as to the accuracy of this determination. As the present variety differs from the previously known species in the same points as L. decagonalis, it need not be compared more closely with them.

planche XII (extrait)

Rumphia ricta (Gregory,1892), Lutétien supérieur, Gironde, 27 mm

Genre Sismondia  Desor,1857

synopsis des échinides fossiles, p.225

Espèce type  Scutella occitana Defrance,1827 (désignation subséquente de Pomel (1883) Classification méthodique et genera des echinides vivants et fossiles, p.72)

Extension stratigraphique (bibliographique, non vérifiée) : Eocène moyen - Miocène inférieur

Syn.

• Sismondaea Meyer-Eymar, 1897, p.2 ; nomen vanum

Sismondia occitana (Defrance,1827), Lutétien supérieur, Gironde, 27 mm

Sismondia archiaci Cotteau,1883, Lutétien , Charente Maritime, 23 mm

Sismondia intermedia Fabre, Lutétien , Médoc, 13 mm

Sismondia testudo Cotteau,1891, Bartonien, Calcaire de Blaye, Médoc, 8 & 10 mm

Sous-famille Neolaganinae  Durham,1954

description succinte : Laganidae avec structure d'assules pseudo-composée sur les ambulacres. Plaques basicoronales arrangées pentagonalement.

Genre Wythella  Durham,1954

Classification of clypeasteroid echinoids, p.682

Espèce type  Laganum eldridgei Twitchell,1915 (désignation originale)

Extension stratigraphique (bibliographique, non vérifiée) : Eocène moyen - fini Oligocène

Whytella eldridgei Twitchell,1915

Laganum eldridgei Twitchell, n. sp.

Plate LXXIV, figures 2a-d.

     Determinative characters. - Test large, subpentagonal to subdecagonal in marginal outline, longitudinally elongate, truncated at the anterior and posterior ends, more or less undulating along the sides. Whole form greatly depressed, margin thin bhut thicker than slightly concave submarginal area, petaloidal region tumid. Apex and apical system subcentral. Lower surface flat. Ambulacral petals long, elongate elliptical, extending two-thirds the way to the margin, pointed and closed at the ends ; pairs of pores conjugated by very narrow more or less wavy grooves. Ambulacral areas very wide at margin, narrowing rapidly to ends of petals. Peristome moderate in size, subcentral, subpentagonal to subelliptical, transversely elongate. Ambulacral grooves apparently simple and straight, each groove having a fine line on both sides which rapidly diverge from the main groove. Periproct relatively large, suboval, longitudinally elongate, one-fourth the way from the margin to the peristome.

     Dimensions. - Length 96 millimeters ; width 75 millimeters ; height 10 millimeters.

     Description. - The only specimens known of this large and handsome Laganum, the largest representative of the genus from American deposits, were collected in Florida by the late G. H. Eldridge of the United states Geological Survey and the species is therefore named in his honor. The test is large, being 3 to 4 inches long and 2^1/2 to 3 inches wide. In marginal outline it is subpentagonal to decagonal, decidedly longer than broad ; margin thin but thicker than the submarginal area, truncated at anterior and posterior ends, more or less undulating along the sides. The whole form is greatly depressed, the upper surface slightly concave around the submarginal area, arising centrally in the form of a low mound which involves the whole petaloidal area ; apex subcentral ; lower surface flat.

     The ambulacral areas are very wide at the margin, being there about four times the width of the interambulacral areas, narrowing rapidly to near the ends of the petals. The petals are long, elliptical in outline, extending two-thirds the way to the margin, pointed and closed at the ends. The anterior pair shorter than the other three, which are subequal in length. The poriferous zones are wide, more than half the width of the rather narrow interporiferous areas, inner row of pores elliptical, outer row very narrowly slitlike, hardly discernible, pairs of pores conjugated by very narrow more or less wavy grooves.

     The interambulacral areas are very narrow at the margin, widen rather rapidly to near the ends of the petals, and narrow again toward the apical region. The whole test is closely set with very small tubercles, among which are scattered at irregular distances some larger ones in deep scrobicules.

     The apical system is subcentral, at the summit of the tumid area. There are four large genital pores, of which the anterior pair are set closer together than the posterior pair. No other details could be made out on the specimens.

     The peristome is of moderate size, subcentral, slightly to the rear of the apical system, subpentagonal to subelliptical, transversely elongate. The details of the ambulacral grooves could not be mad out satisfactorily on the specimens studied. As they leave the peristome there appears to be a single straight groove on each side of which are two fine lines which rapidly diverge from the main groove. These side lines may be the boundary lines of what on better preserved specimens would prove to be finely granulated areas, thus forming a peristomial star.

     The periproct is relatively large, about half the size of the peristome, suboval, longitudinally elongate, situated about one-fourth the way from the margin to the peristome.

     Related forms. - L. eldridgei is readily distinguished from all other American forms. It closely resembles L. elongatum Agassiz, whose origin is unknown and which is not even stated to be fossil, being very similar in size, general form, and marginal outline, but differs from it in having a suboval instead of circular periproct, placed a little farther from the posterior margin.

     Locality. - Suwanee River, Fla.

     Geologic horizon. - Vicksburg group, lower Oligocene.

     Collection. - U.S. National Museum (164683).

Extrait planche LXXIV

Whytella eldridgei Twitchell,1915, Eocène supérieur, Floride, 42 mm

Genre Weisbordella  Durham,1954

Classification of clypeasteroid echinoids, p.682

Espèce type  Peronella caribbeana Weisbord,1934 (désignation originale)

Extension stratigraphique (bibliographique, non vérifiée) : Eocène supérieur

Weisbordella cubae (Weisbord), Eocène supérieur, Hernanco county, Floride, 43 mm