REVISION OF FRESHWATER SPONGES OF SPONGILLIDAE 51 



represented by compact, ovoid, or pedunculate masses of a grayish 

 or whitish color, either fixed to solid supports, or lying free on the 

 bottom. According to these authors, phase two corresponds with the 

 specimens on which the description of S. dementis was based, while 

 phase three is very similar to the sponge originally described as S. 

 yunnanensis. From these most interesting observations it is obvious 

 that the present generic position of S. dementis is far more obscure 

 and uncertain than originally anticipated by Annandale. This prob- 

 lem is unlikely to be solved by the mere revision of those clear-cut 

 genera dealt with in this study, but will have to be approached 

 through a detailed study of all genera, such as Nudospongilla, Corti- 

 spo7igilla, Potamolepis, and Pachydictyum, the gemmules of which are 

 not yet known or perhaps not produced at all. Until such compre- 

 hensive comparative studies can be carried out, it is best to leave 

 S. dementis within the genus originally assigned by Annandale. 



The present authors were unable to confirm or contradict the rec- 

 ord of this species for Africa by Arndt (1936), since material from 

 these localities was unavailable for this study. However, since the 

 African specimens could possibly belong to the E. nitens group of 

 species, the Cameroons record of S. dementis needs yet to be confirmed. 



Genus Corvospongilla Annandale, 1911 



Corvospongilla Annandale, 1911c, p. 122; 1912d, p. 387; 1913.1, p. 78; 1918fi, 

 p. 213.— Gee, 1931e, p. 36; 1932c, p. 27.— De Laubenfels, 1936, p. 36.— 

 Jewell, 1952, p. 445.— Penney, 1980, p. 35. 



Type species. — Spongilla loricata Weltner, 1895. 



Definition. — Megascleres usually robust amphistrongyles, often 

 inflated at their extremities, smooth to granulated, only slightly 

 curved, occasion all}'" amphioxea, exceptionally present in two distinct 

 series. 



Microscleres representing almost straight to slightly curved micro- 

 birotulates with smooth or spined shafts, and a small number of ter- 

 minal recurved spines of varying length; only exceptionally also 

 spined amphioxea, which could well be adventitious. 



Gemmoscleres invariably spined and distinctly curved amphi- 

 strongyla of rather unequal size. 



Gemmules moderately to very large, spherical, with flattened base, 

 or oval in outline; usually found in groups at the base of the sponge 

 and fastened to the support by an outer casing of megascleres or 

 without such a cage; pneumatic coat ill-defined or absent; gem- 

 moscleres embedded in inner gemmular membrane, lying close 

 together as to form a mosaic cover; foramen as a rule tubular and often 

 lateral; occasionally free gemmules also present, usually different in 

 form and structure of pneumatic coat. 



