452 



MR. C. F. JENKIN ON 



[May 12, 



Sheleton.—The dermal skeleton (test-fig. 100) consists of a thni 

 layer of alate triracliates lying tangentially, without orientation. 

 The subdermal triradiates are modified dermal spicules, as m 

 G simplex. The subgastral triradiates are alate, with equal paired 

 rays and an oral angle of 165°. The gastral skeleton (text- 

 fig. 101) consists of a thin layer of sub-regular alate quadri- 

 radiates, lying without orientation. 



Text-fig. 102. 



Grantessa zanzibaris, spicules. X 120. 

 (For explanation of letters see text below.) 



Spicules (text-fig. 102). 



The triradiates are of four sorts : — 



(ffl) Alate triradiates from the dermis. Basal rays straight, 

 65-190 /A long X 8-10 /t thick. Paired rays nearly straight, 

 except for a slight curvature near the junction of the basal ray, 

 rounding the oral angle, 60-130 /a long x 8-9 /a thick. Oral 

 angle 110° to 125°. 



(6) Alate triradiates from the body similar to {a) but with 

 doubly curved paired rays considerably folded. Oral angle 125" 

 to 135°. 



(c) Subdermal triradiates. Basal ray, lying in the dermis, 

 straight, except for an angular bend near the root, 90-140 p. long 

 x8-9/* thick. Centripetal paired ray straight, 120-200^ long 



