126 U-S. NATIONAL MUSEUM BULLETIN 2 72 



Gemmules apparently scarce, scattered through skeletal meshwork, 

 spherical, ranging in diameter 480-530 n; pneumatic layer well de- 

 veloped, consisting of very minute and regular air spaces; gemmo- 

 scleres embedded in this coat in a single, rather dense layer, the longer 

 class protruding through outer surface of pneumatic layer; shape of 

 foramen not reliably observed. 



Distribution. — Apparently restricted to the northern half of the 

 eastern U.S.A. and southern Canada. 



Color in life. — Emerald green. 



Discussion. — The insufficient original description of C. everetti and 

 the comparative paucity of material of this species collected caused 

 most previous authors to believe that the gemmoscleres in this species 

 are homogeneous in length. Even though the length differences between 

 the longer and shorter gemmoscleres of C. everetti are not very pro- 

 nounced, two distinct length groups could be observed on all slides 

 examined. The intimate relationship of this species to those of Hetero- 

 meyenia and Anheteromeyenia is thus quite obvious. 



Extensive material collected in southeastern United States, par- 

 ticularly in South Carolina, seems to possess spicular criteria distinctly 

 different from those displayed by the typical species. A forthcoming 

 comparative study of this material by Harrison (pers. comm.) will 

 decide whether these clearly discernible differences are to be consid- 

 ered of speci&c or subspecific significance. At present it is advisable to 

 consider Corvomeyenia a monotypic genus, even though provisions 

 have been made in the generic definition to include certain criteria 

 displayed by the southern specimens mentioned above. 



Genus Dosilia Gray, 1867, redefined 



Dosilia Gray, 1867, p. 550 (part) .— Annandale, 1911c, p. 110; 1912d, p. 384; 



1918a, p. 213.— Gee, 1931e, p. 37; 1932c, p. 28.— De Laubenfels, 1936, p. 37.— 



Jewell, 1952, p. 450.— Penney, 1960, p. 38. (Not Dosilia Dybowsky, 1884b.) 

 Spongilla Carter, 1849, p. 85 (part). — Bowerbank, 1863, p. 449 (part). 

 Meyenia Carter, 1881a, p. 94 (part) .—Potts, 1887, p. 233 (part). 

 Heteromeyenia Mills, 1888, p. 313 (part). — Weltner, 1895, p. 127 (part). 

 Ephydatia Weltner, 1895, p. 126 (part) .— Kirkpatrick, 1906, p. 226. 

 Asteromeyenia Annandale, 1912a, p. 593. — De Laubenfels, 1936, p. 36. — Gee, 



1931e, p. 32.— Wurtz, 1950, p. 5.— Eshleman, 1950, p. 42.— Jewell, 1952, 



p. 453.— Penney, 1960, p. 33. 

 Astromeyenia Schroder, 1927b, p. 101. 



Type species. — By subsequent designation (De Laubenfels, 1936) 

 Spongilla plumosa Carter, 1849. 



Definition. — Megascleres slender and distinctly fusiform amphi- 

 oxea, either entirely smooth, or covered with minute and scattered 

 spines except at their tips. 



Microscleres present in varying abundance in dermal membrane 



