20 bulletin: museum of comparative zoology. 



alcohol, allowing it to act until the specimens have a light rose color, 

 then wash well in neutral alcohol (90%), clear in cedar oil, and mount 

 in balsam. 



III. CLASSIFICATION. 



Leeches of the family Rhynchobdellidse may be distinguished from all 

 others by the fact that they possess an exsertile proboscis (pr'b., Figure 1), 

 with the aid of which they obtain their food^ for they are entirely with- 

 out jaws such as the medicinal leech possesses. Our common Xorth 

 American species of this family belong to the genus Glossiphonia John- 

 son ('16), better known to many by its synonym Clepsine Savigny 

 ('20). Leeches of this genus have usually a broad flat body, which, 

 when the animal is disturbed, is rolled into a ball. Each somite con- 

 sists typically of three distinct rings ; but the somites at the ends of the 

 body always contain a smaller number of rings. 



These leeches are found in the shallow water of ponds and rivers 

 underneath stones, sticks, or leaves, or adhering to the bodies of their 

 hosts. The smaller species feed upon snails, Crustacea, or other small 

 fresh-water animals ; the larger species are known to feed upon turtles, 

 to whose shells they are often found attached. They probably suck tho 

 blood of other aquatic animals also. 



The following key may aid in distinguishing the species to be 

 described : — 



Key to Species. 



A. Crop diverticula a single pair (after a full meal the animal may have 



five more pairs, inconspicuous, and situated anterior to the prin- 

 cipal pair) ; male and female genital pores separated by a single 

 body ring ; rings without metanieric markings in the living animal. 

 L Eyes two, distinct ; a conspicuous yellowish brown chitinoua 

 spot on the neck dorsally G. stag>iah's (p. 21) 



2. Eyes two, inconspicuously pigmented or entirely without pig- 

 ment ; no chitinous spot on the neck ; body extremely slender and 

 transparent G. elongata (p. 39) 



B. Crop diverticula six pairs ; male and female genital pores separated 



by a single body ring or else united. 



3. Eyes two, the middle (sensory) ring of each somite marked 

 throughout the greater part of the body by a transverse row of 

 whitish spots G.fusca (p. 34) 



