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ECHINODERMATA— ECHINOZOA 



PHYLUM IV 



CoUyrites Desm. (Fig. 412). Test ovoid, tumid, more or less truncated 

 posteriorly. Amh disjunct, the anterior one soraetimes in a slight groove. 

 Width of the Amh increasing towards the ambitus ; pore-pairs in low primary 

 plates. Periproct posterior, supra-marginal, placed in a groove. Apical 

 System elongate, separated by numerous small plates belonging to the 

 postero-lateral lAmb. Yery abundant in the Middle and Upper Jura and 

 Cretaceous. 



Dysaster Ag. Differs from CoUyrites in details of the apical systeni, the 

 genitals not being separated by the antero-lateral ocular plates. Upper Jura 

 and Lower Cretaceous. 



Hyhodypeus Agassiz (Fig. 413). Jura. Infradypeus Gauthier. Upper 

 Cretaceous. Grasia Mich. Jura. 



Fig. 413. 



Hyboclypeus gibberulus Ag, Middle Jura ; Soleure, Switzerland. A, B, Dorsal and ventral views. 

 C, Profile. D, Apical System, enlarged. 



Metaporhinus Mich. Test very tall, slightly longer than broad, sub-cordi- 

 form, projecting upwards anteriorly, grooved and oblique behind. Anterior 

 Amb in a groove, with small, simple, distant pairs of pores ; the other Amb 

 flexuous, with comma-shaped pores placed obliquely to one another. Periproct 

 supra-marginal. Upper Jura and Lower Cretaceous. 



Tribe B. SPATANGOIDEA Duncan. 



Peristome eccentric in front, rarely pentagonal in the adult, usually with a 

 labrum, behind which is a long plasfron bounded laterally by the posterior 

 ambulacra. Ambulacra dissimilar. Inferambulacra with a single plate at the 

 peristomal margin; the postero-lateral areas usually unsymmetrical actinally. 

 Fascioles present or absenf. 



Family 4. Ananchytidae Desor. 



Test ovoid or sub-cordiform in marginal outline, fall or depressed, and with large 

 plates. Ambulacra in a bivium and trivium, nearly similar, flush, apetalous ; pore- 

 pairs largest near the apex and at the peristome, may be uniporous. Periproct 

 variable in position. Cretaceous to Recent. 



Ananchytes Lam. {Echinocorys Breyn.) (Fig. 4 1 4). Test large, oval in marginal 

 outline ; high, rounded or keeled apically, flat actinally. Amb biporous, the 

 pore-pairs well developed abactinally, but becoming smaller, closer and 



