246 



PHYLUM ECHINODERMATA. 



gus purpureus (after Loven from 

 Delage). gtx basal ; mdp mad- 

 reporite ; I-V radii numbered. 



siderable interval, which is occupied by supplementary plates, from 

 the rest of the apical system. Ambulacra similar, Jurassic, Cretaceous. 

 All fossil. Dysaster L. Ag. ; Colly rites Desm. 

 Fam. 2. Plesiospatangidae. Fossil. 



Fam. 3. Ananchytidae. Apical system elongate or compact. Apetal- 

 ous. With or without an anterior groove. Echinocorys Breyn., f ; 



Holaster L. Ag. (Fig. 161), f ; Off aster Desor, 

 f ; Cardiaster Forbes, f ; Urechinus A. Ag., 

 422-1,800 fathoms, Pacific ; Cystechinus A. 

 Ag., f and r ; 1,000-2,000 fathoms ; Calymne 

 W. Thorns., r, 2,650 fathoms, N. of Bermuda. 

 Fam. 4. Spatangidae. Usually heart- 

 shaped and with an anterior groove. Apical 

 system with four or less perforated plates ; 

 compact or with the madreporite variable 

 in its posterior extension ; radials five and 

 external. The test is longer than broad 

 and bilateral symmetry is marked. The 

 anterior ambulacrum is always different 



FIG. 174. Apical region of Spatan- f rO m the other four, which may be petaloid 



abactinally. Fascioles are present in most 

 genera, but they may be absent ; and the 

 genera may be grouped according to this 

 feature and their arrangement if present. They begin in the Lower Creta- 

 ceous, and reach their highest development at the present day. 



Recent Genera. 



Platybrissus Grube ; Palaeopneustes A. Ag., Caribbean Sea ; Hemiaster 

 Desor, f and r ; Faorina Gray, China ; Linthia Merian, f and r ; Schizaster 

 L. Ag., f and r ; 

 Agassizia Val., f /, c 



and r ; Moira A. 

 Ag., f and r ; Moi- 

 ropsis A. Ag. ; Bris- 

 sus Klein, f and r ; 

 Meoma Gray, f and 

 r ; Metalia Gray, 

 f and r ; Rhinobris- 

 sus A. Ag. ; Bris- 

 sopsis L. Ag., f and 

 r ; Spatangus Klein, 

 f and r, S. purpureus 

 Leske, 5-530 fms., 

 Channel Islands, 

 North Sea, etc. ; 

 Maretia Gray, f 

 and r, 25 to 800 

 fathoms ; Eupa- 



tagus L. Ag., f and r, Australia ; Macropneustes L. Ag., f and r, Caribbean ; 

 Nacospatangus A. Ag., Linopneustes A. Ag. ; Cionobrissus A. Ag. ; Echino- 

 cardium Gray, f and r, littoral to 2,675 fathoms, worldwide ; Breynia 

 Desor, f and r ; Lovenia L. Ag. and Desor, f and r, 10-28 fathoms. 



The following are apetalous : Genicopatagus A. Ag., Antarctic; Palaeo- 



FIG. 175. Pourtalesia je'Jreysi (from Delage, after Loven). / 

 anal Semite ; prc periproct ; 3, 4, 5 third, fourth and fifth in- 

 terradii. 



