No. l.J G. M. DAWSON — CANADIAN SPONGILL*5. * 



often abruptly bent, entirely spined, length nearly 0.003 in. ; 

 spines scattered, rather large, conical, acute, generally retrorse 

 near the ends of the spicula. Ovarian spicula scarcely distin- 

 guishable from the interstitial and dermal. 



Hab. y River St. Lawrence, near Montreal. 



This species is of the type of the European S. lacustris, but 

 differs sufficiently from that species. It also differs markedly 

 from S. Dawsoni and S. Ottawaensis. Its ovarian and dermal 

 spicula are intermediate in size between those of the last named 

 species. 



Fig. 4. — a., ordinary skeleton-spiculum. 6., a second form of 

 skeleton-spiculum, smaller and perhaps not fully developed. 

 B., C, ovarian and dermal spicula. 



Spongilla Ottawaensis, sp. nov. Specimens do not show the 

 external form. Colour in the dried state, green. Skeleton-spi- 

 cula acerate, slightly arcuate, often rather abruptly and bluntly 

 pointed, smooth, length, 0.011 to 0.008 in. Ovaria sub-globose, 

 rather irregular, large, diameter 0.04 in.; spicula cylindrical, 

 stout, slightly and regularly arcuate, entirely and rather densely 

 spined, length 0.0034 ; spines rather prominent, somewhat ob- 

 tuse. Dermal and interstitial spicula like the ovarian, but 

 slightly more delicate. 



Hah., L'Orignal, on the Ottawa River. 



The skeleton-spicula are shorter than those of S. Dawsoni ; 

 the ovarian etc. spicula much larger than those of that species, 

 and larger also than those of S. flexispina. They somewhat 

 resemble those of S. lacustris, but are distinctly truncate at the 

 extremities. The specimens are small, but densely filled with 

 large ovaria. 



Fig. 6. — a., ordinary skeleton-spicula. A., ovarian spicula. 



