REPORT ON THE ECHINOIDEA. 



245 



Showing how sharply the continental genera contrast ^\'ith those of the littoral faunae. 

 Of the 72 genera represented in the different littoral faunse only 9 are common to 

 both the littoral and continental ranges, when we separate the species which are 

 littoral, and happen to extend either into or through the continental range into the 

 abyssal range, and as these species are very numerous, considerable care must be taken 

 to separate them from the continental species. They are added to the continental lists, 

 and are marked L.+ when extending only into the continental range, and L.++ when they 

 extend also into the abyssal range ; while when we compare the littoral genera and the 

 abyssal we find only two genera, Asthenosoma and Hemiaster, which have strictly 

 characteristic littoral species. 



Comparing in the same way the continental and the abyssal ranges, the following 

 genera found in the continental range do not extend into the abyssal : — 



Dorocidaris. 



Goniocidaris. 



Scdenia. 



Cceloiileurus. 



Microinjga. 



Temnechmus. 



Hemipedina. 



Neolamixis. 



Conoclypus. 



Catopygus. 



Paleopneustes. 



Spatangus. 



Nacop>cttagxis. 



Echinocardium. 



Rhinohrissus. 



Agassizia. 



Schizaster. 



Moiropsis. 



That is, in addition to the 9 genera of which there are representative species in both 

 the Httoral and continental ranges, there are 11 genera eminently characteristic of the 

 continental range ; while the following genera have representative species both in the 

 continental and abyssal ranges : — 



Porocidaris. 

 Podocidaris. 

 Asjndodiadema. 



Asthenosoma. 

 Phormosoma. 

 Trigonocidaris. 



Or only 6 genera thus far out of 47 which are found extending from the continental 

 line to the abyssal range and including both ; whde the following genera are eminently 

 abyssal, and have thus far not been found to extend into the continental range among 

 the recent species. 



Spatagocystis. 



Prionechinus. 

 Cottaldia. 

 Pygaster. 

 Pourtalesia. 



EcMnocrepis. 



Urechinus. 



Cystechinus. 



