The Productivity of Fish Food in Oneida Lake 173 



which to distinguish Physa heterostropha, for the present spe- 

 cies, Physa integra, and others, are without this feature or have 

 it but feebly developed in some specimens. As species go in 

 PJiysa warreniana seems as distinct as many of those recog- 

 nized and there is apparently no reason why it should be con- 

 sidered a race of ancillaria. It is a common species in the 

 lakes of the middle west and probably extends eastward as do 

 many of the fresh-water pulmonates. It is the predominating 

 species of the genus in Oneida Lake. 



66. Physa integra Haldeman. 



Integra occurred on boulder, sand, clay, and mud bottoms 

 in water one-half to ten feet deep. It was most abundant on 

 a sand bottom in water one and a half feet deep, and on a clay 

 bottom in two feet of water. The majority of individuals were 

 young or immature (3-5 mm.) and were frequently associated 

 with algse (CEdogonium, Chara, Nitella) or with the larger 

 vegetation. In the lagoon east of the steamboat wharf (Habi- 

 tat No. cxv) they were found on Fotamogeton interruptus and 

 Myriophyll'um verticillatum. 



Considerable variation has been noted among the adult indi- 

 viduals of this species. Haldeman's type, figured by Binney 

 ('65, p. loi, fig. 172) has an elongated, sharp spire and a 

 narrow shell. In Oneida Lake this species varies from the 

 Haldeman type to a shell with short spire and broad body 

 whorl. Fhysa billingsi Heron, judging by examples so named 

 by Crandall in the collection of Dr. Walker, is an absolute 

 synonym. Physa niagarensis Lea may be a distinguishable 

 variety though none were found in Oneida Lake which could 

 be referred to this race. All of the Physas are in need of a 

 thorough revision which should include an examination of 

 available types as well as the working out of the genitalia, 

 radulse, and other internal organs. Full suites of the various 

 species from many localities are also necessary. 



*67. Physa heterostropha Say. 



Six young Physas 3-4 mm. long were collected in Tuttle 

 Brook, a small tributary of Chittenango Creek, in a mass of 

 algse {CEdogonium and Cladophora). The shells are smooth 



