CHAP. IV.] ST. THOMAS TO BERMUDAS. 259 
boomerang. These spicules are distributed in all parts of the 
sponge, and are particularly abundant near the insertion of the 
coil. No analogous form occurs in the other species of //y- 
alonema. 
The large Amphidisct are much larger than in any other 
known sponge. They are upward of half a millimetre in 
length, and visible to the naked eye—twice as large as in //. 
Lusitanicum. The feathered shafts of the five-rayed spicules 
Fia. 67.—Hyalonema toxeres, Wy VILLE Tuomson. Lower surface of the sponge. Natural size. 
(No. 24.) 
which fringe the openings are longer than in the other species, 
and the rays of the cross are much shorter (Fig. 68). 
The second specimen of the sponge-body agreed with the one 
deseribed in all essential points of structure, but was more con- 
ical in form. The young specimen (Fig. 69) differed from the 
young of //. Lusitanicum of the same age in being wider and 
more cylindrical; but the external wall, which afterward be- 
comes that of the lower surface, showed the same arrangement 
in squares which we find in the young of the other species, so 
