My. H. J, Carter on the Suhspherous Sponges. 25 



250-1800ths long by 2|-1800th8 of an inch broad) ; occasionally- 

 pointed only at the distal and rounded at the other end, awl- 

 shaped : b, d, slender, bifid and trifid respectively ; shaft pointed, 

 460 long by 1 broad ; rays 6 long by § broad, all pointed : 

 c, slender, trifid recurved, shaft pointed, 320 long by | broad ; 

 rays 6 long by ^ broad, all pointed. 



Fig. 5. The same, characteristic spicule of the body ; straight, smooth, 

 fusiform, pointed at each end, 250 long by 2^ broad : a, occa- 

 sional spicule, fusiform awl-shaped, roimd at one extremity, 

 pointed at the other, or rounded more or less at both encfs. 

 These two spicules also enter into the composition of the crust. 



Fig. 6. The same ; very minute spicules and siliceous globules, most nu- 

 merous in the matted sti*ucture of the crust ; the former like bits 

 of thread, sigmoid and semicircular respectively, more or less 

 contorted; largest sigmoid form l-2000th mch long by l-24000th 

 inch broad ; siliceous globule 1 -6000th inch in diameter. 



Fiff. 7, The same; occasional spicules somewhat larger than the last, 

 found in the sarcode generally : a, shaft semielliptical, incurved 

 and pointed hook-like at the extremities, more or less contorted ; 

 largest 10-6000ths inch long : b, direct, half-lateral, and lateral 

 views respectively of a similar but more complicated hooked 

 form ; shaft consisting of three curves, of which the central is 

 the largest ; extremities trifid, rays expanded and webbed toge- 

 ther like a waterfowl's foot, incurved in the opposite direction 

 to the external curvatures of the shaft, which are the reverse of 

 the central one ; 6-6000ths inch long. 



The latter is an intricate form, but easily understood by 

 drawing the curves &c. in accordance with the description. 



Fiff. 8. The same, real lengths of the spicules respectively : a, bifid and 

 trifid extended ; b, trifid recurved ; c, body-spicule. (See figs. 

 4 and 5 respectively. 



Fiff. 19 (PL II.). The same, foi-m of gemmule (?), showing nuclear, 

 opaque, or white portion, enclosed in a transparent capsule 

 charged with extremely minute, bacillary, pointed, spiculiform 

 bodies; 4-1800ths inch in diameter; bacillary body l-6000th 

 inch long. 



Fiff. 20 (PI. II.). The same, trifid spicule of surface, bearing sponge- 

 substance charged with nucleolated cells ; largest cells about 

 1 -3000th inch in diameter. 



Fiff. 9. Geodia ( Ci/clonimn, Gray) arabica, n. sp, (PI. I.), natural size; 

 dried specimen, found on the sea-shore, probably after having 

 been much exposed to friction in the waves, as no dermal sar- 

 code remained upon it ; showing surface uncovered by dermal 

 sarcode, dimpled over with little pores, and here and there 

 larger ones, probably the vents (oscules) or terminations of the 

 efferent canals. AU much smaller than during the living state, 

 the reduction in size having been produced b}' contraction in 

 diying. 



Fig. 10. The same, section to show internal structure (taken from an- 

 other specimen) : a, crust composed of globular crystalloids, 

 covered with dermal sarcode charged with minute spicules ; 



b, zone of trifid spicules of different forms supporting the crust ; 



c, sponge-substance of the body supported on stout curved fusi- 

 form spicules arranged more or less m a direction radiating from 

 the centre, presenting the truncated canals of the efferent or 

 excretory system ; d, central portion more compact than the 

 rest. 



