ECHINOCAUDIUM PENXATIFIDUM. 581 



abactinal pole is anterior ; the internal fasciole surrounds a broad, flat, 

 triangular, internal plastron, extending to the edge of the vertically truncated 

 anterior extremity. The abactinal part of the test is nearly horizontal from 

 the anterior edge of the fasciole, and the confluence of the posterior zones 

 of the posterior lateral ambulacra. The posterior interambulacrum rises as 

 a rounded keel above the general level of the upper part of the test. The 

 posterior extremity is bevelled ; the anal system vertically elongate. The 

 subanal plastron extends in a sharp beak beyond the general outline of 

 the test. The bare posterior actinal ambulacral avenues are broad ; actinal 

 surface flat. 



The lateral anterior ambulacra descend nearly perpendicularly along the 

 sides of the test ; this, and the short posterior interambulacral keel, distin- 

 guish E. mediterraneum from E. pennatifidum. 



Mediterranean. 



Echinocardiimi pennatifidum 



? Amphidotits gibbosui (Barrett), 1857, Ann. Mag. N. H. (non Agass.) 

 ? Echinocardium pennatifiduni Norm., 1868, 4th Dredg. Rep. Shetland. 

 (See Part II. p. 351.) 



PI. XX. f. 1-2; PI. XXXII. f. 16. 



Northumberland ; Straits of Florida. 



