168 ECHINOIDEA. 



The smaller tubercles on the dorsal surface are very delicate, but 

 not distinctly smaller close to than at a distance from the ambitus. 

 The tubercles of the lower surface have the same general characters 

 as in S. purpureus, but are not so large. 



Distribution. Atlantic — Norway, Azores, Portugal, Agulhas Bank, 

 Cape of Good Hope. 30(?)-200 fms. 



a, b. Off coast of Kerry, 100-200 fms. Royal Irish Academy. 

 c-u. S.W. Ireland, 100, 110, 180 fms., July 1889. ' Flying Fox' Exp. * 



v. 54 miles off Achill Head, 500 fms. Royal Dublin Soc. 



iv. 30 miles off Achill Head, 144 fms. Royal Dublin Soc. 



x, y. 45 miles off Blackrock, 500 fms. Royal Dublin Soc. 



z,a' . 40 miles off Bolus Head, 115 fms. Royal Dublin Soc. 



b'. Shetland. J. Gwyn Jeffreys, Esq. 



4. ECHINOCARDIUM. 



Echinocardiiun, Gray, Ann. Phil. xxvi. (1825) p. 430; id. Cat. Brit. 



Had. (1848) p. 6 ; id. Cat. Rcc. Ech. (1855) p. 42 ; Al. Ay. Rev. Ech. 



(1S72) pp. 109 & 349; Cams, Prod. Eaun. Mediter. (1884) p. 102; 



Dune. J. L. S. xxiii. (1889) p. 261. 

 Spatagus (pars), O. F. Mull. Prod. Zool. Dan. (1776) p. 236. 

 Amphidetus, Ay. Mem. Soc. Neueh. i. (1836) p. 184; [Amphidotus, 



Forbes, Brit. Star/. (1841) p. 190] ; Ay. $ Des. Ann. Sci. Nat. viii. 



(1847) p. 11. 



Test never large, rather thin, cordiform, truncated and highest 

 behind ; the paired ambulacra triangular in outline, with few large 

 pores ; anterior ambulacrum in a groove, which may or may not be 

 deep. Spines mostly silky. 



Key to the Species. 



a. Anterior ambulacrum in a groove. 



Antero-lateral ambulacra with, generally, 7 an- 

 terior and 10 posterior pores ; postero- 

 lateral with 9 outer, and 8 or 9 inner .... 1. E. cordatum. 



b. Anterior ambulacrum not in a. groove. 



Antero-lateral ambulacra with, generally, 6 to 



8 and 12 to 15 pores ; postero-lateral with 



14 and 12 2. E. pennatifidum. 



Antero-]ateral ambulacra with, generally, 5 to 



6 and 9 to 10 pores ; postero-lateral with 



7 and 6 3. E.jlavescens. 



