ECHTNOIDEA. CIDAROIDA. 241 



Fam. 4. Diadematidae. Regular, ectobranchiate, with or without 

 vestiges of internal branchiae ; shell highly ornamented ; ambulacra 

 usually narrower than inter ambulacra, with vertical rows of primary 

 tubercles, and usually consisting of compound plates, all the components 

 of which are primaries ; the pore-pairs are usually in a simple row, and 

 sometimes in double rows only near the mouth and apex. Inter ambu- 

 lacra also with vertical rows of primary tubercles. Teeth grooved, jaws 

 without a closed pyramidal foramen, feet heteropodous. Chief distribution 

 in Jurassic, Chalk and Tertiary. 



Diadema Schynvoet, with blue patches (ocellar) on the shell, f and r, 

 most seas ; Centrostephanus Ptrs., r ; Placodiadema Duncan, f ; Hetero- 

 diadema Cotteau, f ; Codiopsis L. Ag., f ; Pleurodiadema De Loriol, f ; 

 Magnosia Michelin, f ; Coltaldia Desor, f ; Diplopodia McCoy, f ; Pedi- 

 nopsis Cotteau, f ; Acanthechinus Duncan and Sladen, f ; Phymechinus 

 Desor, f ; Asteropsis Cotteau, f ; Diplotagma Schliiter, f ; Micropyga A. 

 Ag., r, 100 to 600 fathoms, Philippines, Fiji ; Plistophyma Peron and 

 Gauthier, f ; Pedina L. Ag., f ; Echinopedina Cotteau, f ; Stomechinus 

 Desor, f ; Micropedina Cotteau, f ; Heterocidaris Cotteau, f ; Echinoihrix 

 Peters, r, East coast Africa, Pacific Islands, Red Sea, etc. ; Astropyga Gray, 

 r, Panama, California, Zanzibar, etc., with overlapping plates ; Poly- 

 cyphus L. Ag., f ; Codechinus Desor, f ; Orthopsis Cotteau, f ; Eodiadema 

 Duncan, f ; Peronia Duncan, f ; Echinopsis L. Ag., f ; Gymnodiadema 

 De Loriol, f. Progonechinus Duncan and Sladen, f, allied here. 



Fam. 5. Cyphosomatidae. Contains only one recent genus, Coptosoma 

 Desor, f and r ; and the following extinct genera. Cyphosoma L. Ag., 

 Gauthieria Lambert, Thylechinus Pomel, Micropsis Cotteau. 



Fam. 6. Arbaciidae. Test depressed abactinally, flat actinally ; 

 epistroma with granules, projecting ridges, sessile glassy knobs. Apical 

 system large ; periproct oval and oblique, composed of four triangular 

 plates ; pore in ocular plates double. Ambulacra straight, narrow, ex- 

 panding near the peristome ; pore-pairs simple or in large arcs or crowded 

 actinally ; plates compound near the ambitus ; in the compound plates 

 the middle component is a large primary, while the aboral and adoral 

 components are demiplates, or the primary is adoral and the demiplates 

 are aboral to it. Sphaeridia solitary or numerous. Peristome large, in- 

 curved at the sides of the ambulacra. Teeth keeled ; auricles not closed 

 above. Tertiary and recent. Arbacia Gray, f and r ; Echinocidaris 

 Duncan and Sladen, r, most seas ; Coelopleurus L. Ag., f and r ; Podoci- 

 daris A. Ag., r, 150 to 1,075 fms., Caribbean, Philippines; Dialiihocidaris 

 A. Ag., deep sea. 



Fam. 7. Temnopleuridae. Regular ectobranchiate with the teeth 

 keeled, and auricles closed. Ambulacra with triple compound plates. 

 The suture of the ambulacral and interradial plates and of the apical 

 system grooved and may be pitted, or there may be a raised ornamentation, 

 costulate or reticulate or in ridges, the sutures being furrowed or not. 

 Cretaceous to recent. Glyphocyphus J. Haime, f ; Dictyopleurus Duncan 

 and Sladen, f ; Arachniopleurus Dun. and Slad., f ; Ortholophus Duncan, 

 f. ; Paradoxechinus Laube, f ; Echinocyphus Cotteau, f ; Zeuglopleurus 

 Gregory, f ; Lepidopleurus Dun. and Slad., f ; Coptophyma Peron and 

 Gauthier, f ; Trigonocidaris A. Ag., r, Florida, Caribbean, etc. ; Temno- 

 pleurus L. Ag., f and r, Indian Ocean, Persian Gulf, Pacific ; Pleurechinus 

 L. Ag., f and r ; Temnechinus Forbes, f and r ; Salmacis L. Ag., f and r, 

 Red Sea, Ind. Ocean, etc. ; Salmacopsis Doderlein, r ; Mespilia Desor, 



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