REPORT ON THE CALCAREA. 55 



Leuconia multiformis, var. ca/pillata. 



Outer surface fur-like ; osculum usually fringed with fine linear acerate spicules ; 

 gastric skeleton consisting mainly of the quadriradiate form. 



Leuconia multiformis, var. amorpha. 



Gastric skeleton, besides triradiate and quadriradiate, consisting also of minute 

 acerate, spicules, sometimes lying isolated, sometimes filling all the interstices between 

 the triradiate and quadriradiate spicules just mentioned. Outer surface more or less 

 bristly. The minute acerate spicules are occasionally to be found in the parenchyma 

 and on the outer surface too. 



One of the specimens belonging to the variety goliath attains a length of 233 mm., 

 and is the largest calcareous sponge hitherto known. The external form of the varieties 

 goliath and capillata is that of an elongated tube; the specimens of the variety amorpha 

 in the collection are of irregular outline, rather sac-like. The varieties amorpha and 

 goliath are from Bermudas, the variety capillata from Zebu. 



Skeleton. — The skeleton consists of gastric quadriradiate and triradiate, of subgastric 

 triradiate, of quadriradiate and triradiate spicules belonging to the parenchyma, of 

 dermal triradiate, of large acerate, of minute acerate, and of fine linear acerate spicules 

 of the peristome. 



Gastric quadriradiate and triradiate spicules. — Basal ray straight, tapering from the base to a 

 sharp point, usually half as long as lateral rays, with a diameter of 002 mm.; lateral 

 rays slightly curved inwards, of rather cylindrical form, yet sharply pointed, each forming 

 with basal ray an angle of 100° to 105°, average size - 45 by - 015 mm. ; apical ray of the 

 same thickness (0015 mm.), curved, sharply pointed, length varying from to 015 mm. 



Sutgastric triradiate spicules — Sagittal; all rays of the same average diameter (0 - 035 mm.), 

 smooth, tapering from the base to an approximately sharp point ; basal ray straight, 

 its length not exceeding 0"75 mm.; lateral rays undulating, forming with each other an 

 angle varying from 180° to 150°, rarely exceeding 045 mm. in length. 



Quadriradiate spicules of the parenchyma. — To be found only in the walls of the exhalent 

 canals, too rare to be of any systematic significance ; usually of the form and size of 

 gastric quadriradiate spicules, sometimes twice as long and thick, with lateral rays curved 

 outwards; this latter form is connected with the common gastric quadriradiate by inter- 

 mediate stages. 



Triradiate spicules of the parenchyma. — All rays of the same average diameter (0'065 mm.), 

 either lying in the same plane throughout their whole length or bent in such a manner 

 that the plane of the junction of the rays is different from that of their ends ; 

 sharp-pointed, rarely longer than 0*7 mm., the comparative length of basal ray being 

 slightly inconstant ; some quite regular, the greater part sagittal, the angle formed by 

 basal and each of lateral rays varying from 120° to 110°. There are also in the paren- 



