486 Illinois State Ijahoratory of Natural History. 



includes the most essential features : The preocular region 

 is very light colored, with a bright orange spot, sometimes 

 including the eyes. The light yellow areas are chiefly con- 

 fined to a median- longitudinal stripe, to marginal spots, and 

 to a pair of series of spots or blotches between these two. 

 Sometimes the median band is continuous for the whole 

 length, sometimes its middle part disappears, and sometimes 

 small remnants of it remain at the ends only. It is of very 

 irregular width, alternately expanding widely at intervals of 

 about three somites and contracting between. The marginal 

 spots are generally very regular, of somewhat triangular 

 shape, and extend over the two annuli which lie between the 

 successive neural annuli, the latter being dark colored at the 

 margins. It is only at the ends of the body that they suffer 

 modification. The intermediate series are the most variable. 

 They may be formed of small spots including the dorso- 

 lateral sensilla^, and occurring on the neural* annuli of every 

 somite or only on every second or third somite ; they may 

 extend over a 3 as well as a 2 or they may become large 

 irregular blotches reduced in number and extending over 

 several somites ; they may coalesce more or less into irregular 

 longitudinal stripes which are likely to be constricted on 

 a 1 ; and they may unite in various ways with the mar- 

 ginal spots or with the median band. The ground color 

 may greatly predominate or almost disappear. 



Habits. — This very common leech is found most frequently 

 adhering to the plastron or naked parts of the skin of 

 various species of turtles, to which it clings very tenaciously. 

 In the early spring, before and during the period of produc- 

 tion of spermatophores and oviposition, they feed eagerly 

 and gorge themselves with blood. Like other species of 

 similar habit they not infrequently kill their host by thus 

 draining its blood. At other seasons they may be kept for 

 months without food. Not infrequently this species is also 

 found on floating wood in ponds and ditches or under stones 

 in streams, where it feeds on small oligoch.etes, etc. 



