Mr. H. J. Carter on the SubspJierons Sponges. 27 



efferent or excretory system ; e, nucleus, consisting of densely- 

 interwoven sponge-fibre and spicules, resembling the cortical 

 portion in appearance and composition. 



Fiff. 4. The same, characteristic spicule of the sponge generally ; straight, 

 smooth, more or less fusiform, awl-shaped ; seldom if ever 

 pointed at both ends, although frequently much attenuated; 

 shorter and more abruptly terminated on one side than on the 

 other, the enlarged end round, sometimes inflated. Size, 70 to 

 120 long by I to 2 broad : a, largest, real length. 



The distal ends of those spicules which, projecting beyond the 

 cortical portion, appear to be always broken off, probably do not 

 differ from the one just described, as no other foi-m of long spi- 

 cule than this is to be found in any other part of the sponge. 



Fiff, 5. The same, large stellate crystalloid, more or less scattered through- 

 out the structure, but most numerous at the point of contact 

 between the cortical and body portions ; rays more or less in 

 number, often undulated, and sometimes bifid at the extremities. 

 Total diameter 1 to 6 ; central globule or body of largest 2 in 

 diameter ; ray 2 long ; body and rays all smooth, clear, and 

 crystalline. 



Fig. 6. The same, minute stellate crystalloid, relatively magnified, to 

 compare with the foregoing ; 2 to 4-6000ths inch in diameter : 

 a, more magnified view ; b, ray still more magnified, to show its 

 rough spinous sui-face. 



Fiff. 7. Pachymatisma Johnstonia, Bowerbank (PI. 11.), natural size of 

 specimen : a, view of the exterior, showing pores and large 

 vents ; b, section through the centre, showing thickness of crust 

 and cut portions of the efferent or excretory system of canals. 

 Structui'e amorphous, massive ; centre imdistinguishable. 



Fiff. 8. The same, section of interior, more magnified, to show the cha- 

 racter of the efferent system of canals. 



Fig. 9. The same, portion of surface more magnified : a, part of crust 

 uncovered by dermal sarcode, showing the pores only ; pores 

 l-24th inch in diameter and about l-12th inch apart, but slightly 

 variable both in size and proximity : b, portion covered with 

 dermal sarcode, charged with the minute, rough, fusiform spi- 

 cules peculiar to the species; pores beneath faintly, if at all, seen 

 in the fresh state. 



Fiff. 10. The same, portion of the surface covered by the dermal sarcode, 

 greatly magnified, showing the papillary apertures of the afferent 

 or incurrent canals dispersed over it generally, but more parti- 

 cularly over the area covering the pore, which is situated in the 

 centre, averaging about l-32nd part of an inch in diameter; 

 papillary apertm-e about l-900th inch in diameter, but slightly 

 variable in size. 



Fiff. 11. The same, pore gi'eatly magnified, surrounded hj the globular 

 crystalloids of the crust, showing : — a, the diaphragmatic exten- 

 sion of the sarcodal lining, and b, its central opening ; the former 

 very variable, 10 to 2-5 in diameter, and the latter more constant, 

 averaging 6 in diameter. 



Fiff. 12. The same, vertical section of pore, showing hourglass-shaped 

 cavity covered in externally with dermal sarcode and opening 

 below into one of the areolar cavities at the circumference of 

 the sponge : a, external chamber of hourglass cavity ; b, internal 

 chamber, opening into areolar cavity; c, dermal sarcode sur- 

 mounted by papillary apertures ; d, diaphragm of pore ; c, spiral 

 opening in the same, more or less extended, but in this instance 



