Genre   Pliolampas Pomel, 1888

Notes d'échinologie synonymique, p.446

Espèce type  Echinolampas gauthieri Cotteau, 1880, par monotypie.

Echinides nouveaux ou peu connus, p.227

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

Syn. 

• Breynella Gregory, 1891, p.600. Espèce type : Pygorhynchus vassalli Wright, 1855 ; synonyme subjectif plus récent

• Milletia Duncan, 1891, p.191. Espèce type : Echinolampas elegantulus Cotteau, 1883 ; synonyme subjectif plus récent

 Pygorhynchus Vassalli, Wright, n. sp.

Test oblong, wider behind than before ; interambulacrum produced into a caudal elongation ; petaloid portions of the ambulacral areas narrow and short ; sides tumid ; anus small, round, nearer the inferior border than the dorsum, with a projecting beak-like process arching over its upper border, and an oblique truncature of the lower part of the border below ; base slightly concave ; mouth pentagonal, nearly central ; oral lobes small ; rays of the poriferous star around the margin short.

     Dimensions. - Antero-posterior diameter 13/20 inch, transverse diameter 7/10ths of an inch, height nearly 6/10ths of an inch. Most of the specimens average only from one-half to two-thirds of these dimensions. The large specimen before us is the most perfect we have examined.

     Description. - This small Urchin has an oblong form ; it is rounded before, a little enlarged towards the junction of the middle with the posterior third, which is produced into a caudal process. The sides are tumid, and the upper surface is flattened ; the petaloid portions of the ambulacras areas are nrrow and short, and form only a star on the dorsum ; the single and postero-lateral areas are nearly alike in width and length ; the antero-lateral pair are rather wider and shorter, they are 7/20ths of an inch in length, and are slightly curved forwards and outwards ; their poriferous zones contain eighteen pairs of pores, arranged in narrow rows, and not united by any apparent slit. The postero-lateral areas are 8/20ths of an inch in length, and their zones contain twenty pairs of pores; these areas are directed much backwards, which makes the width of the lateral interambulacra proportionally greater. The apical disc is nearly central, but nearer the anterior border ; it has four large genital pores, and five well-marked eye-holes. The single ambulacrum is almost identicalin length and width with theposterior pair ; the apices of all the ambulacra are rather rounded than landeolate. The lateral interambulacra we have said are very wide, but the single interambulacrum is narrow, and forms a conspicuous prolongation of beak-like process, which arches over the upper border of the round anal opening, situated rather below the middle of the posterior border, in an oblique truncature of the test : this beak-like process

is not seen in the small specimens before us ; it would therefore appear to be a character of the adult condition only. The base is slightly concave towards the mouth, which is situated nearer the anterior border ; it has a pentagonal form, with five small oral lobes covered with tubercles ; between them, the temrinations of the ambulacra form five short poriferous petals. The tubercles on the upper surface are small and irregularly disposed on the plates ; those on the base are a little larger, especially in the vicinity of the mouth.

     Affinities and differences. - This species resembles Catopygus fenestratus from the upper chalk of Ciply, Belgium, but is distinguished from it by having the sides more tumid and the upper surface flatter ; the posterior border is likewise more produced ; it distinctly differs from it however in having the base slightly concave, and the oral lobes less developed. It differs from Nucleolites (Pygorhynchus) subcarinatus, Goldf., from the middle tertiaries of Bünde, in having more tumid sides, a less concave base, and a different form of the anal opening. From the very brief notice of Catopygus conformis, Desor, from the tertiaries of Orglande, it is impossible to form any idea how far it may resemble that form, at it is neither figured nor described, but merely entered in the "Catalogue raisonné" with this remark : "Mais l'anus est un peu plus bas, et la face supérieure plus surbaissée."

     Locality and stratigraphical position. - Collected from bed No. 1, Malta, where it is extremely rare. Specimens are in the collection of the Geological Society, the Jermyn Street Museum, and the cabinet of Earl Ducie. We dedicate this species to Dr. Vassalo of Malta, under whose judicious care and continued research the public collection of Maltese fossils has been greatly enriched.

Pliolampas vassalli (Wright, 1855) - Miocene, Albacete, Espagne, 22 mm

Pliolampas vassalli (Wright, 1855) - Miocene, Albacete, Espagne, 25 mm

Genre   Studeria Duncan, 1891

A revision of the genera and great groups of the Echinoidea, p.185

Espèce type  Catopygus elegans Laube, 1869, par monotypie.

Ueber einige fossile Echiniden von den Murray Cliffs in Sud-Australien, p.8

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

Syn. 

• Hypselolampas Klark, 1917, p.104. Espèce type : Studeria recens Agassiz, 1879 ; synonyme subjectif plus récent

• Tristomanthus Bittner, 1892, p.41. Espèce type : Nucleolites subcarinatus Goldfuss, 1826, p.42 ; synonyme subjectif plus récent

Genus STUDERIA Duncan

Studeria Duncan, 1891. Journ. Linn. Soc. (Zool.), vol. 23, p. 185. Type species by monotypy, Catopygus elegans Laube.

Synonyms : Hypselolampas Clark ; Phaleropygus De Loriol ; Tristomanthus Bittner.

generic description

     Small to medium, elongate, smoothly rounded anterior margin, pointed or slightly truncated posterior, adorally depressed around peristome, moderately inflated ; apical system anterior, monobasal, three genital pores, no pres in left anterior genital plate ; petals long, straight, extending almost to margin, open, adjacent pore pairs widely spaced, ambulacral plates beyond petals single pored ; periproct marginal, longitudinal, slight groove extending adorally ; peristome anterior, slightly higher than wide ; bourrelets very strongly developed, inflated ; phyllodes slightly widened, single pored, with few pores ; buccal pores present ; tubercles slightly larger adorally, no naked, granular zone in interambulacrum 5.

     Comparison with other genera. - Studeria is very similar to Pliolampas, as both genera have open petals, usually three genital pores with no pore in the left anterior genital plate, similar phyllodes, and a higher than wide peristome. Studeria

differs in having a marginal periproct, and more developed bourrelets. Perhaps these differences are not of sufficient importance to warrant maintenance of Studeria.

     Remarks. - Mortensen (1948, p. 234), along with many earlier workers, considered Studeria recens A. Agassiz as the type species of Studeria. However, as Duncan mentions only one species, S. elegans, in his original description of this genus, S. elegans must be the type species by monotypy.

     I have been unable to find any specimens of the type species but include below a description of a very similar species, S. subcarinatus (Goldfuss).

     Range and distribution. - Oligocene to Recent of Europe, Egypt, and Australia.

Studeria elegans (Laube, 1869) - Miocène inférieur, Mannum formation, Mypolonga, Australie du Sud, 16 mm

(Coll. J.F. D.) Studeria elegans (Laube, 1869) - Miocène inférieur, Mannum formation, Murray River, Australie du Sud, mm

Studeria elegans (Laube, 1869) - Oligocène, Alicante, Espagne, 25 mm

Studeria subcarinata (Goldfuss,1826) - Oligocène, Alicante, Espagne, 24 mm

Studeria subcarinata (Goldfuss,1826) - Oligocène, Alicante, Espagne, 22 mm

Studeria subcarinata (Goldfuss,1826) - Oligocène, Westphalie du Nord, Allemagne, 31 mm

Studeria spratti (Wright,1864) - Upper Globigerina limestone, Phosphorite conglomerate bed, Malte, 15 mm