-Mr. H. .1. Carter on Spomjes. '23 



EXl'LANATloN C)l' THE i'LATEd. 

 Platk I. 



Fii/. 1. TrichiHft/psut riliosa, n. >,'. ot sp., outline of, natuml size. 



/Yy. 1'. The 8am»', iimjriiiHed two (liaiiK>t(>n* : a, vent. 



J^. S. The siiino, vent more maguilied, to show disposition of osciUes 

 opeIUIl^^ into it. 



/^'y. 4. The same, spicule of, linear, sli^rhtly sinuous, inivqui fusiform, 

 spino-tuberculated at the ends. .Sizt> l-(10th of iin incli lung bv 

 l-100(.)th broad. Scale l-24th to l-(JO(X)th of an inch. 



Fig. 5. I^tuvuia Johiuitonii, n. sp., outline of, natural size. 



Fig. 0. The same, niafrnitied 2 diameters: a, ciliated vents; h, uuoiliated 

 vents ; r, larjre quadriradiate spicule of the surface, relatively 

 mag'nitied. 



Fig. 7, The same, diajTram of vertical section of upper third or cloacal 

 extremity : a, cloaca branchin<r ott" into b o, excretory canals ; 

 c f, excretory apertures; </ f/ </ </, parietes of cloaca, consisting 

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

 cloacal arms of ^eat quadriradiate spicule. 



For the arranjremeut of the spicules round the wwciliated vent 

 see tig. 40, PI. II. 



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

 maguitied, showing large and small apertures in them : a a, ef- 

 ferent apertm-es. 



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

 to show the dermal sarcode (a), and its pore-openings (6). 



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

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

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

 arm foreshortened, presenting the centi*al canal line ; e, large, 

 thick, slightly curved, imequiacerate spicule of the ciliated crown 

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

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

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

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

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

 which projects into the cloacal cavity and excretory canals, in 

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

 nute quadriradiate spicule with one short arm. 



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

 the scale of l-12th to 1-OOOOth of an inch : a, 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 from 

 Lencosolenia nivea. Scale l-24th to l-1800th of an inch. 

 Fig. 13. Grantia compressd. Sponge-cellsrelatively 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 



