120 U.S. NATIONAL MUSEUM BULLETIN 2 72 



the megascleres, seem important enough to consider A. pictovensis a 

 distinct and separable "form." Its specific status, erected by Potts 

 (1885a, 1886) and MacKay (1885, 1886, 1889), is herewith restored. 



Anheteromeyenia biceps (Lindenschmidt, 1950) 



Plate 10, figures 11, 12 

 Heterome^jenia biceps Lindenschmidt, 1950, p. 214. — Penney, 1960, p. 43. 



Material. — Type specimen (USNM). 



Description. — Sponge, according to Lindenschmidt (1950), form- 

 ing shallow cushions of small dimensions; surface comparatively even, 

 oscula small. Skeleton forming an irregular network, joined together 

 by small amounts of spongin. Consistency of live sponge recorded as 

 rather firm, texture compact. 



Megascleres subfusiform to cylindrical amphioxea, ranging from 

 smooth to microspined, their tips always entirely smooth; length 

 range 260-310 n, width range 15-17 m. 



Microscleres absent. 



Gemmoscleres birotulates of two distinct classes, both in regard 

 to length and shape; the longer class with stout cylindrical shafts, 

 usually microspined, and terminally mth a bulbous swelling bearing a 

 dense arrangement of coarse and rather blunt spines; the smaller 

 class with extremely slender shafts slightly longer than the diameter 

 of the rotules, and occasionally protrude beyond them ; and terminally 

 with flat rotules consisting of a smaller number of long rays, the latter 

 often subdivided; length range of longer class 30-42 n, width of shaft 

 4-5 ju; length range of shorter class 23-26 n, width of shaft 2 n, of 

 rotule 20-22 n. 



Gemmules abundant in basal parts of mature sponge, spherical, 

 ranging in diameter 350-380 n; pneumatic layer well developed but 

 not very high, consisting of minute subspherical air spaces; gem- 

 moscleres embedded in this layer radially, the longer class often 

 inserted at a slanting angle; foramen more or less simple, without 

 discernible tube, only slightly elevated. 



Distribution. — Found only in the type locality, the inlet and 

 outlet of Douglas Lake, Michigan, U.S.A. 



Color in life. — Recorded as ranging from yellow to green. 



Discussion. — The intrageneric relationship of this spongillid, 

 known from only one locality, is at present difficult to assess. Because 

 of the heterogeneous structure of its gemmoscleres and the absence of 

 microscleres, the authors have little hesitation in placing this species 

 in the genus Anheteromeyenia; its affinities to the other known con- 

 geners have yet to be demonstrated. 



The extremely fragile shafts and irregularly incised rotules of the 

 shorter set of gemmoscleres, the unusual form of the longer set, and 



