E. IMPERIALIS. — SPICULATION. 75 



The gastralia are oxypeutactins sparingly supplied with 

 minute prickles at tlie conically pointed ends of rays. The 

 paratangentials (200-450/^ long, 13-15/^ thick) are frequently of 

 unequal length in the same spicule and more or less bent so as 

 to form an irregular cross. The unpaired, distally directed ray 

 is straight and somewhat longer. As in all other species of the 

 genus, the gastralia are nowhere so regularly arranged as to form 

 a quadrate meshed latticework. Quite similar pentactins extend 

 into the excurrent canals as canalaria, which become more and 

 more sparse toward the distal end of the canals. 



The floricomes look exactly like those of other Euplectella. 

 In diameter they measure 90-105 p., say about 97 /'- on the average. 

 Only in very young specimens have I found them perceptibly 

 smaller (84-91 /-« dia.), but never so small as in E. marshaUL 

 The number of terminals to each principal ray varies from 7 to 

 12. The terminal plate shows 5-9 sharp teeth on the external 

 edge, while its internal edge is represented by a simple obtuse 

 rounding of the surface, as is usual with all floricomes (PI. II, 

 fig. 14d). 



In sections of a specimen 210 mm. long, I have found in 

 abundance cases of the floricome in various stages of developing 

 its terminals (figs. 10-12, 14). They were all situated in the 

 subdermal trabecular space, which undoubtedly is the place where 

 the rosette in question arises and reaches full development, 

 eventually to be moved off to the apex of the hilt-ray of the 

 dermalia. In the earliest stage observed, the six princi^^als were 

 already fully developed though still somewhat thinner than in 

 the mature state. Each principal, traversed throughout by the 

 axial canal, terminated externally in a lenticular disc, from the 



