unequal in length und occasionally one is aborted and the spi- 

 cule is bifid. I have not noticed any specimens of this form 

 with compound or bifurcate rays. There is considerable va- 

 riation in the size of these spicules ; a large specimen (fig. 1 7) 

 measured 3,15 mm. long by 0,09 mm. wide. A smaller form 

 (fig. 19) is 1,01 mm. long and the thickness of the shaft is 

 0,045 mm - 



A spicule closely resembling fig. 1 7 is figured by Dr. Bow- 

 erbank from Geodia Zetlandica (Mon. Brit, spong. Vol. Ill, 

 p. 15, PL VII, fig. 8). 



Geodia? sp. 



(Plate II, fig. 1 6). 



Spicule with a delicate, straight, gradually tapering shaft 

 and three slender simple rays, unequal in length and recurved, 

 each of the rays being of nearly the same thickness as the 

 shaft, Length (incomplete) 1,05 mm. ; width 0,067 mm. Very 

 rare. This spicule is of the same character as the preceding, 

 but the arms are recurved, anchor-like. 



Tethya? sp. 



(Plate III, figs. I, 2, 13, 14). 



Simple trifid spicules with a relatively very variable length 

 of shaft, which is straight or curved, gradually tapering and 

 in most instances obtusely pointed; the arms of the head 

 rays are very long, frequently of unequal length in the same 

 spicule; stout, conical, curved, pointed and directed forwards 

 at a very open angle with the shaft. There is a very great 

 amount of variation in the length and in the relative propor- 

 tion of the arms of these spicules; in some examples, one of 

 the rays becomes nearly as long as the shaft. In no instance 

 do the arms bifurcate. The length of one of the largest 

 specimens (fig. 2) is 4,025 mm.; width of shaft 0,247 mm,; 

 width of head rays 1,35 mm. In another form (fig. 13), in 

 which the shaft is constantly straight and but little stouter 

 than the arms, the total length of the spicule is 1,8 mm. dia- 



