FEBSH-WAÏEE SPONGES. 93 



1881. Meijenia fluvialilis, Carter. 



1882. Ephijdatia fluviatilis, Dybowski. 



1882 Meijenia jhivînlilis var. acuminata, Potts. 



1883. Ephydaiia jluviatilis, Vejdovski. 



1883. Spongilla fluvialilis, Retzer. 



1884. Ephydaliafluvialilis, Wierzejski. 



1885. Meyenia fluviatilis, var. Mexicana, Potts. 



1885. " " " anguslibirotulata. Carter. 



1885. " " " gracilis, Carter. 



1885. " " MacKay. 



1886. Ephydatia fluviatilis, Petr. 

 188t. Meyenia fluvialilis, Potts. 



Sponge greeuish, in massive cusliionlike enm'ustation, often extensively lobular but 

 never decidedly branching. Pores and osteoles conspicuous, surface often showing 

 canals covered by the dermal film only. Texture rather firm. Skeleton spicules fascicu- 

 lated, about 0.01 inch long, curved, fusiform, gradually pointed, varying from smooth to 

 entirely or centrally spinet!-. No dermal or flesh spicules. Statoblasts numerous, es- 

 l^ecially towards the base, spherical and variable in size. Crust thick to thin or even 

 none, embedding one, two or more concentric layers of short birotulates with their large, 

 flat, irregularly-rayed rotules tangential to the chitinous capsules, that is, with their 

 axes normal to the chitinous coat — in the radial direction. Length of birotules 0.0005, 

 diameter of rotules O.OOOY inch. 



Habitat. — In lakes, ponds and flowing "water. Very common. Next to S. lac?/slris in 

 its universality. Nova Scotia and Newfoundland. — G. M. Dawson. Paquette Eapids, 

 Ottawa River. — H. M. Ami. The Nimpkish liiver, Vancouver Island — G. M. Dawson. 



Genus III.— HKTEROMEYENIA, Potts. 



Statoblasts as in Meyenia only having two classes of birotulate spicules, generally 

 difTering in shape and in length. 



*7. — Heteromeyenia argyrosperma. 



1880. Spongilla argyrosperma, Potts. 



1881. Heteromeyenia " " 

 1885. " " MacKay. 



Sponge minute, pale greenish, encrusting. Skeleton spicules rather slender, sub- 

 fusiform, abruptly pointed, sparsely spiuiferovrs, about 0.01 inch long, statoblasts rather 

 large. The greater birotulates are very robust, over 0.005 inch in length, shafts long, often 

 bent, and occasionally bearing strong irregular spiues. Rays of the rotules one to four, 

 assuming the form of strong, claw-like hooks, recurved and incurved. The lesser bi- 

 rotules are nearly 0.003 inch in length, abundantly spined, rotules flatter and irregularly 

 hooked. 



Habitat. — On submerged sticks, Garden of Eden. Lake, Pictou Co., Nova Scotia. — 

 MacKay. 



