FEE8H-WATEE SPONGES. 89 



1880. Spongilla segregala Potts. 



1883. " contecta, Eetzer. 



1884. " fragilis, Yejdovsky. 



1885. " fragilis, MacKay. 

 1885. " Lordii, Wierzejski. 

 1885. " fragilis, 



1885. " " Peter. 



188G. " ghmeralu, Noll. 



188*7. " fragilis. Potts. 



Spouge greenish, cncrustiug, thicker towards the I't'utre of its area — sometimes 

 au iueh or more. Pores and osteoles numerous, the latter large. Skeleton spicules 

 slightly curved, cylindrical, acerate. smooth, about 0.008 of an inch long. Statoblasts 

 about 0.02 inch in diameter, generally in " pavement layers " at the base of the 

 sponge, with their foramina extended into short tubules and directed upwards ; sometimes 

 in compact subglobular clusters, the foraminal tubes always opening outwards. Cellular 

 crust of statoblasts charged with spined spicules about 003 inch long, nearly cylindrical, 

 truncate or cone-pointed and slightly curved. 



Habitat. — Still or flowing water. The third in point of commonness, everywhere. 

 Nova Scotia and Newfoundland. — MacKay. The St. Lawrence, the Ottawa and the Lake 

 of the "Woods. — G. M. Daicson. Lake Osogoos, Cascade Mountains, British Columbia.— 

 Boicerbatik. 



2.— Spongilla MacKayi. 



1885. Spongilla MacKayi, Carter. 

 1885. " " MacKay. 



188Y. " " Potts. 



Sponge green, encrusting, thin, charged with large subglobular compound bodies 

 about one-twelfth of an inch iu diameter, made up of IG or 20 statoblasts, more or less. 

 Skeleton spicules acerate, slightly curved, sharp-pointed about 0.009 by 0.0004 inch. 

 Statoblasts globular, with short flaring foraminal tubules all opening inwards into the 

 central cavity of the compound body formed by them, which body is supported by densely 

 spined statoblast spicules of various sizes w^hich, intercrossing, form a nestlike, globular 

 covering around the whole. Statoblast spicules, much like those of the skeleton, but 

 becoming much shorter and more strongly spined as they approach the chitinous coat, 

 where they may be reduced to nearly 0.004 inch iu length, but may increase to 0.0007 

 inch in breadth, wnth very strong and irregular spines, so that the spicule sometimes 

 appears nearly as broad as long. 



Habitat.— Yugini^i Pond, St. John's, and lakelets between Conception Bay and 

 Trinity Bay, Newfoundland ; lakelet, Pictou Co., Nova Scotia.— ilf«cAfl^. Spicules of, in 

 diatomaceous deposits in the lakes which supply the waterworks of Halifax. NS. — 

 Prof. Lawson. 



Sec. IV, 1S89. 12. 



