26 Mr. H. J. Carter on the Subspherous Sponges. 



Fig. 11. The same, portion of surface more magnified : a, part of crust, 

 showing pores uncovered by dermal sarcode ; 6, portion covered 

 with dermal sarcode charged with minute, smooth, curved fusi- 

 form spicules, pointed at each end ; c, form of dermal spicule 

 more magnified, size 18 to 25 long by \ broad. (To compare in 

 size with body-spicule (fig. 15), which is ten times as long.) 



For more details of the dermal sarcode and pores, see illustra- 

 tions of Pachymatisma Johnstania, PI. II. 



Fig. 12. The same, globular crystalloid of the crust, oval obtuse, com- 

 pressed in the axis of the umbilicated central depression : a, ver- 

 tical section, shovsdng : — the crystalline nature of the body, tra- 

 versed by faint lines radiating from the centre ; the umbilicated 

 depression below ; also the margin, formed of the clavate tuber- 

 cles of the surface. Size, 8 long by 7 broad and 5 thick. 



For the development and further illustration of this body, 

 see that of Pachymatiwia, PI. II. 



Fig. 13. The same, minute stellate crystalloid with which the structure 

 generally is more or less charged, particularly towards the cir- 

 cumference, 1 to 6-6000ths inch in diameter : «, not unfrequent 

 form, 3 to ll-6000ths inch in diameter. 



Fig. 14. The same, forms of distal ends of the spicules of the zone (fig. 

 10 b) which supports the crust, respectively ; all smooth and 

 pointed ; proportionally magnified : a, robust, triradiate ; shaft 

 straight, 265 long by 7 broad ; rays more or less slightly undu- 

 lated, 15 long by 6 broad : b, end view of head, to show tri- 

 radiate form, shaft truncated : c, trifid extended, less robust ; 

 shaft straight, 420 long by 3 broad ; ray 5 long by 1 broad : 

 d, trifid recurved, shaft much the same as the last, straight, 

 370 long by 2 broad ; ray 5 long by 1 broad (these spicules are 

 arranged in groups ; and there are about five to eight of the more 

 slender forms, c and d, to one of the robust, a) : e e, occasional 

 forms. 



Fig. 16. The same, characteristic spicule of the body ; stout, curved, 

 smooth, fusiform, pointed at each end ; size 205 long by 4 broad. 



Fig. 16. The same, real lengths of the spicules respectively : a, trifid ex- 

 tended ; b, trifid recurved ; c, triradiate ; d, body-spicules. (See 

 figs. 14 and 15 respectively.) 



Plate II. 



Fig. 1. Tethya (Donatia, Gray) lyncurium, Lam., natural size : a, view of 

 exterior, showing lobate or warted surface ; b, vertical section, 

 showing the cortical portion pierced by the expanded bundles of 

 spicules, which, radiating from the centre or nucleus, terminate 

 by broken extremities on the surface. 



Fig. 2. The same, portion of the surface more magnified, showing by the 

 dotted points the broken ends of the spicules as they traverse 

 the wart-like lobes, and the depressions in the interaugular 

 spaces where the pores and vents are respectively situated. 



Fig. 3. The same, vertical section, more magnified, showing : — a, cortical 

 portion formed of sponge-fibre horizontally interwoven with the 

 expanded ends of the bundles of spicules radiating from the 

 centre — the whole so dense as to assume the appearance and 

 consistence of cartilage ; b, sponge-substance of the body sup- 

 ported on the radiating bundles of spicules, which overlap each 

 other and present between them the truncated canals of the 



