Mr. H. J. Carter on Sponges. 25 



EXPLANATION OF THE PLATES. 

 Plate I. 



Fig. 1. Trichogypsia villosa, n. g. et sp., outline of, natural size. 



Fig. 2. The same, magnified two diameters : a, vent. 



Fig. 3. The same, vent more magnified, to show disposition of oscules 

 opening into it. 



Fig. 4. The same, spicule of, linear, slightly sinuous, insequifusiform, 

 spino-tuberculated at the ends. Size l-60th of an inch long by 

 1-lOOOth broad.- Scale l-24th to l-6000th of an inch. 



Fig. 5. Leuconia Johnstonii, n. sp., outline of, natural size. 



Fig. 6. The same, magnified 2 diameters : a, ciliated vents ; h, unciliated 

 vents ; c, large quadriradiate spicule of the surface, relatively 

 magnified. 



F^g. 7. The same, diagram of vertical section of upper third or cloacal 

 extremity : a, cloaca branching off" into h h, excretory canals ; 

 c c, excretory apertures ; dddd, parietes of cloaca, consisting 

 chiefly of areolar cells ; e, ciliated crown of vent ; f, internal or 

 cloacal arms of great quadriradiate spicule. 



For the arrangement of the spicules round the wnciliated vent 

 see fig. 40, Pl. II. 



Fig. 8. The same, diagram of areolar cells of parietes of cloaca, much 

 magnified, showing large and smaU apertures in them : a a, ef- 

 ferent apertures. 



Fig. 9. The same, diagram of a portion of the surface, much magnified, 

 to show the dermal sarcode («), and its pore-openings (5). 



Fig. 10. The same ; a-f, all the spicules relatively magnified, viz. on the 

 scale of l-24th to l-1800th of an inch : a, large quadriradiate 

 spicule of surface ; b h, curved arms ; c, internal arm ; d, straight 

 arm foreshortened, presenting the central canal line ; e, large, 

 thick, slightly curved, ineequiacerate spicule of the ciliated crown 

 of vent ; f, thin, straight, cylindrical one of the same ; g, tri- 

 radiate, staple spicule of the skeleton, of various sizes, showing 

 the curved and straight arms respectively, the latter (A) bearing 

 the trace of the central canal ; i, small quadriradiate of the in- 

 terior, front view ; i', lateral view, showing the curved arm, 

 which projects into the cloacal cavity and excretory canals, in 

 company with k, minute fusiform spicule, and /, still more mi- 

 nute quadriradiate spicule with one short arm. 



Mg. 11. The same, minute spicules more, but relatively, magnified, on 

 the scale of l-12th to l-6000th of an inch : «, curved fusiform 

 spinous spicule, for the most part characterized by one extremity 

 presenting the appearance of having been fractured towards the 

 point and reunited in the opposite direction to the general 

 curvature of the shaft ; b, quadriradiate spicule, showing its 

 short arm &c. 



Fig. 12. The same, dark or transparent area (according to the direction 

 of the light) at the imion of the four arms of the great quadri- 

 radiate spicule of the surface, arising from the presence of the 

 fourth arm, which thus distinguishes at once this species ftom 

 Leucosolenia 7iivea. Scale l-24th to l-1800th of an inch. 



Fig, 13. Grantia compressa. Sponge-cells relatively magnified, on the scale 

 of l-12th to l-6000th of an inch, showing : — a, cell containing 

 granular mucus or protoplasm, nucleus, and contracting vesi- 

 cles ; b, rostrum ; c, collar or frill ; d, cilium — all polymorphic ; 

 e, another common form ; /, a form where the whole cell nearly 



