14 FOSSIL ECHINI OF THE WEST INDIES. 



SYSTEMATIC DESCRIPTIONS. 



REGULAR OR ENDOCYCLIC ECHINI; THE CIDAROIDA 

 AND CENTRECHINOIDA. 



The fossils occurring in the West Indies comprise very few of the 

 regular or endocyclic Echini, although 7 species of cidarids occur and 

 there are indications that more will be found ; of the Centrechinoida, * 

 however, the remains are extremely rare, Echinometra prisca being 

 the only species known from a considerable amount of material. In 

 the collections studied, I have seen only one other species of the order 

 Centrechinoida, namely, Echinopedina cubensis, from the Dominican 

 Republic (known also from Cuba). Cotteau records 3 additional 

 species from Cuba, not known elsewhere in the West Indies. 



Key to the West Indian Families of Fossil Regular Echini, the Cidaroida and Centrechinoida. 

 Tubercles perforate. 



(Cidaroida) 



Ambulacra composed wholly of simple primary plates Cidaridce 



(Centrechinoida) 

 (Aulodonta) 



Ambulacra composed in part at least of compound plates Pedinidce 



Tubercles imperforate. 



(Stirodonta) 



No primary tubercles above the ambitus Hemicidaridce 



Many primary tubercles above the ambitus. 



Periproct with large suranal plate Saleniida 



Periproct without large suranal plate. 



Ambitus circular Phymosomatida 



(Camerodonta) 

 Ambitus elliptical Echinometrida 



Under the Cidaridae 7 fossil species are recognized (see key, p. 15). 

 Under the Pedinidae there is only 1 fossil species, Echinopedina cubensis. 

 Under the Hemicidaridae there is only 1 fossil species, Codiopsis 

 arnaudi. Under the Saleniidae there is only 1 fossil species, Salenia 

 scutigera. Under the Phymosomatidae there is only 1 fossil species, 

 Phymosoma cubensis. Under the Echinometridse there is only 1 fossil 

 species, Echinometra prisca. 



Order CIDAROIDA Duncan, 1889. 



Family dDARIDjE Gray, 1825. 



Genus CIDARIS Leske, 1778. 



Type species.— Echinus cidaris Linne, 1758, Sys. Nat., ed. 10, p. 664. 



Of the genus Cidaris, 7 species are definitely known as described, 

 occurring fossil in the West Indies. In addition, a few spines have 

 been found which are not referable to any of the known species. 



1 The ordinal name Centrechinoida and the family name Centrechinidae are taken from 

 Centr echinus, a name proposed by Jackson (1912, Phytogeny of the Echini, p. 27) to replace 

 Diadema, which name is not available for Echini, being preoccupied. 



