246 



PHYLUM ECHINODERMATA. 



lit 



FIG. 174. Apical region of Spatan- 

 gus purpureus (after Loveu from 

 Delage). gtx basal ; mdp niad- 

 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. ; Collyrites 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 ; Offaster 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 

 from the other four, which may be petaloid 

 abactinally. Fascicles 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 ^ s 



and r ; Moira A. ^ 



Ag., f and r ; Moi~ 

 r ops is A. Ag. ; Bris- 

 sus Klein, f and r ; 

 Meoma Gray, f and 

 r ; Metalia Gray, 

 f and r ; RMnobris- 

 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 andr, 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 ; Breyn in 

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



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



FlG. 175. Pourtalesia jef/reysi (from Delage, after Loven). / 

 anal Semite ; prc periproct ; 3, J, o third, fourth and fifth in- 

 terradii. 



