208 Universitij of California Publications in Zoology [Vol. 11 



and 5 mm. in width. It is an exceedingly active species, and 

 very extensile, the body when extended being ten times as long 

 as broad. It is found in Europe, the adjacent parts of Asia and 

 Africa, and in North and South America. The material secured 

 in connection with the work in this paper was obtained from 

 an artificial lake in Golden Gate Park, San Francisco. The 

 specimens were found clustered by the hundreds underneath the 

 stones along the margin of Stow Lake. When brought into the 

 laboratory they are rather more difficult to keep alive than are the 

 Diiia above mentioned. The water must be frequently changed, 

 and the animals fed more often than in the case of the Dina. 

 Earthworms provided the best food material, especially since 

 these are readily procured and the leeches feed voraciously upon 

 them. As compared with other living material, I have found 

 leeches remarkably easy to keep for long periods in good condi- 

 tion. For this reason they provide an exceptionally favorable 

 material for experimentation. 



IV. CATEGORIES OF MOVEMENTS IN LEECHES 



1. Basis for Classification 

 The repertoire of movements in the leech is not a very exten- 

 sive one, though the different responses show a wide range of 

 modifiability in both vigor and duration. These reactions may 

 be classed as the random side-to-side (lateral) and up-and-down 

 (vertical) movements the crawling or "looping" reaction, the 

 "swimming" response, the undulatory respiratory movements, 

 the feeding responses, and the breeding reactions. The general 

 features of all of these categories of responses have been studied, 

 with the exception of the behavior during the breeding season. 

 Unfortunately, the material for the nephelid studied showed no 

 tendency toward breeding, though kept in the laboratorj' through 

 a period of several months. In the case of the species of Glossi- 

 phonia and Hemiclepsis used in this study, specimens were found 

 carrying their eggs and also their young. This fact afforded the 

 opportunity for the study of the jMSsibilities of the presence of 

 a rudimentary "parental instinct." 



