THE ECHINOIDEA 321 



FAMILY 3. CASSIDULIDAK. Asternata with closed, petaloid ambulacra ; 

 a floscelle is present. SUB-FAMILY 1 . CLYPEINA. Genera Clypeus, Leske ; 

 Clypeopycjus and Faujasia, d'Orb. ; Pseudodesorella, Etallon ; Pyyurostoma, 

 Cott. & Gauth. ; Pyyurus, Ag. SUB-FAMILY 2. CASSIDULINAE. Genera 

 Australanthus, Bittner ; Breynella, Greg. ; Cassidulus, Lam. ; Eurhodia, 

 Archiac & Haime ; Paralampas, Dune. & Slad. ; Pygorhynchus, Ag. ; 

 Rhynchopygus, d'Orb. ; Stigmatopygus, d'Orb. SUB -FAMILY 3. CATCK 

 PYGINAE. Genera Catopygus, Ag. (Fig. XVI. 8) ; Neocatopygus, Dune. 

 & Slad. ; Phyllobrissus, Cott. ; Pseudocatopygus, Cott. & Gauth. ; Stu- 

 deria, Dune. SUB- FAMILY 4. ECHINOLAMPINAE. Genera Conolampas, 

 A. Ag. ; Echinolampas, Gray ; Heteroclypeus, Cott. ; Microlampas, Cott. ; 

 Craterolampas, Cott. ; Milletia, Dune. ; Neolampas, A. Ag. ; Oriolampas, 

 Munier-Chalmas ; Palaeolampas, Bell ; Phylloclypeus, Lor. ; Plesiolampas, 

 Dune. & Slad. ; Vologesia, Cott. & Gauth. SUB- FAMILY 5. EOLAM- 

 PINAE. Genera Archiacia, Ag. ; Asterostoma, Ag. ; Claviaster, d'Orb. ; 

 Eolampas, Dune. & Slad. 



SUB-ORDER 2. STERN ATA. 



Atelostomata with the peristome eccentric anteriorly (usually bilabiate). 

 No floscelle ; anterior ambulacrum different from the rest. A sternum is 

 present. Fascicles sometimes present. 



FAMILY 1. COLLYRITIDAE. Sternata without floscelle. There is a 

 rudimentary meridosternum. The anterior ambulacrum is narrower 

 than the others. Apical system disjunct ; the three anterior ambulacra 

 grouped together as the "trivium," and the two postero- lateral am- 

 bulacra as the " bivium." There are no fascicles. Genera Collyrites, 

 Desmoulins ; Dysaster, Ag. (Fig. XVI. 6) ; Grasia and (?) Metaporhimis, 

 Michelin ; Pygorhytis, Pomel. Owing to the disjunct apical system, this 

 family has completely lost the radial symmetry, and presents some 

 remarkable resemblances to the Pourtalesiidae. It appears, however, 

 probable that while the Collyritidae have descended from some primitive 

 asternate form allied to Hyboclypus, the Pourtalesiidae are degenerate 

 forms of Prymnodesmian Sternata. 



FAMILY 2. ECHINOCORYTHIDAE. Meridosternous, labiate Sternata, with 

 an elongate apical system, and the ambulacra separated into a bivium 

 and trivium. Fascioles present in some genera. Genera Calymne, 

 Wy v. Thorns. ; Cardiaster, Forbes ; Coraster, Cott. ; Cystechinm, A. Ag. ; 

 Eclmwcorys, Leske (syn. Aiianchytes, Lam., Fig. XXXV. 2) ; Enallo- 

 pneustes, Pomel ; Enichaster, Lor. ; Entomaster, Gauth. ; Galeaster, Seunes ; 

 Guettaria, Gauth. ; Hagenovia, Dune. ; Hemipneustes, Ag. ; Holaster, Ag. 

 (sub - gen. Sternotaxis, Lamb.) ; Infulaster, Hagenow ; Jeronia, Seunes ; 

 Lampadaster, Cott. ; Offaster, Desor ; Oolaster, Laube ; Ovulaster, Cott. ; 

 Stegaster, Pomel ; Stenonia, Desor ; Tholaster, Seunes ; Urechinus, A. Ag. 



FAMILY 3. SPATANGIDAE. Sternata with anterior ambulacrum re- 

 duced ; apical system compact ; sternum either amphisternous or merido- 

 sternous. SECTION 1. ADETINAE. Spatangidae without fascioles. Genera 

 Archaeopmustes, Greg. ; Clypeanthus, Cott. ; Echinocrepis, A. Ag. ; Enallaster, 

 d'Orb. (Fig. XVI. 7) ; Epiaster, d'Orb. ; Genicopatagus, A. Ag. ; Hemipatagus, 

 Desor; Heterolampas, Cott.; Isaster, Desor ; Macraster, Roem. ; (?) Megalaster, 



