234 University of California Publications in Zoology [Vol. 11 



on dii¥erent species. That such is certainly the case, however, 

 is very easily demonstrated and one can verify it as often as he 

 likes on almost any species of Clepsine that happens to be acces- 

 sible. ' ' 



Houghton (1863) early recorded the fact that some of the 

 Glossiphonidae possess the rudiments of an "incubating" and 

 "parental" instinct. Castle (1900) records several observations 

 in regard to the egg-laying process in the species Glossiphonia 

 stagiialis. In the vicinity of Cambridge, Massachusetts, he notes 

 the egg-laying period a.s being chiefly in the months of April 

 and May, though extending to as late as September. The eggs 

 are attached in groups to the under surface of the body. Each 

 group is enclosed in a delicate transparent sac. these sacs being 

 arranged in two longitudinal rows placed close together. The 

 egg-laying occurs at night in animals kept in acjuaria and was 

 not observed. The number of eggs laid appears to depend upon 

 the size of the animal, varying from sixteen to forty-five in 

 number, with an average record of thirty-one. 



Castle (1900) says with regard to the mode of fecundation 

 in Glossiphonia stagnalis: "Whitman (1891) has shown that in 

 the case of G. parasitica (Clepsine plana) the contents of the 

 spermatophore pass through the integument into the body cavity, 

 and that impregnation probably occurs while the egg is still in 

 the ovary. A similar process doubtless occurs in the case of 

 Glossiphonia stagnalis. " 



Moltschanov (1911) has recently given his observations on 

 some features of the breeding behavior of certain European 

 species of the genera Glossiphonia and Eemiclepsis. He finds 

 upon sectioning the body of adults of these two genera that there 

 are modified epidermal cells, which in their arrangement permit 

 of the more ready and effective attachment of the suckers of 

 their young. He also suggests as probable that the young derive 

 their sustenance for the first third of their growth period from 

 the secretions of the ventral secretory cells of the adult body. 

 As evidence of this he records that the young can live only a 

 short time when removed from the parent body. BoLsius (1911) 

 mainly confirms the results of Moltschanov. He believes, how- 

 ever, that the mortality among the young as the result of removal 



