36 



HAWAIIAK AND OTHER PACIFIC ECHINI. 



Station 4083. Off Puniawa Point, Maui. 238-253 fathoms. Gy. s. 



Station 4085. Off Puniawa Point, Maui. 267-283 fathoms. S. sh. 



Station 4090. Off Mokuhooniki Islet, N. E. approach Pailolo Channel. 

 Bott. temp. 43.8'. 304-308 fathoms. Fne. gy. s. 



Station 4096. Off Mokuhooniki Islet, N. E. approach Pailolo Channel. 

 Bott. temp. 45. 3^ 272-286 fathoms. Fne. gy. s. 



Station 4097. Off Mokuhooniki Islet, N. E. approacli Pailolo Channel. 

 Bott. temp. 44. 2\ 286 fathoms. Fne. gy. s. 



Station 4116. Off Kahuku Poinr, N. W. coast of Oahu. Bott. temp. 

 48.8°. 241-282 fathoms. Cor. s. for. 



Station 4117. Off Kahuku Point, N. W. coast of Oahu. Bott. temp. 45.6°. 

 253-282 fathoms. Cor. s. for. 



Bathymetrical range, 202-346 fathoms. Extremes of temperature, 

 51.7°-43.8°. 



Twenty-seven specimens. 



Aporocidaris a. Ag. and Clark. 



The discovery of a cidaroid in deep water off Kamchatka very similar to 

 Porocidaris Millcn A. Ag. calls attention with new emphasis to the pecu- 

 liarities of that form, and makes it seem desirable to establish a genus for 

 the reception of the two species, in order to make more clear the features 

 in which they differ from Porocidaris. The extraordinary size of the abac- 

 tinal system, which is from .60 to .70 of the horizontal diameter of the test; 

 the small number of ambulacral plates, which are usually fewer than 30 

 and only in the largest specimens exceed that number; the fact that the 

 poriferous zones are scarcely sunken at all ; the very slender but rough 

 primary radioles ; the nearly cylindrical or even club-shaped secondaries 

 and miliaries ; and the absence of any sort of tridentate pedicellaria?, com- 

 bine to make the line between these species and the other Cidaridie 

 remarkably distinct. They are small and rather delicate cchinoids, appar- 

 ently confined to very deep water. 



