CASTLE: NOKTH AMERICAN RHYNCHOBDELLID^. 51 



6. Glossiphonia parasitica Sat (1824). 



Plate 1, Figs. 2, 3a, 3 6; Plate 2, Fig. 6; Plate 8, Figs. 32, 33, 37. 



Hirudo parasitica Say ('24) ; Clepsine parasitica Diesing ('50) ; C. plana 

 Whitman ('91^) ; ? C. chelydrs Whitman ('91=^). 



a. Habitat, Form, Size, 



This large and conspicuously colored leech is the commonest and most widely 

 distributed of our North American species of Glossiphonia. It is often found 

 adhering to the bodies of turtles, whose blood it sucks, or underneath stones in 

 pools and streams frequented by turtles. It is referable to the genus Placobdella , 

 Blan chard ('94), if one recognizes the validity of that genus. In it are included 

 probably several forms which because of their close relationship I choose to call 

 varieties. One of these has been carefully described by Whitman ('91") under 

 the name '' Clepsine plana." In what follows I hope to supplement that de- 

 scription and add the description of another form which is commonly found 

 associated with it. The two varieties agree completely, so far as I can deter- 

 mine, in form, size, and constitution of somites, but can be distinguished in my 

 collections by constant differences in roughness of surface and in color pattern. 



In general form the body in this species is very broad and flat. Whitman 

 describes it correctly in the case of large individuals as " ovate-elliptical in con- 

 traction, emarginate posteriorly." In the case of small individuals, however, 

 or of large individuals well extended, the emarginate condition is not present 

 (Figure 6, Plate 2 ; Figure 37, Plate 8 ; Figure C, p. 56). The dimensions 

 given by Whitman for the largest individuals, I can substantiate: "Length at 

 rest, 5-6 cm.; width, 2.6 cm." I have an alcoholic specimen (var. rugosa) from 

 Lake Chautauqua, N.Y., which measures 5.6 cm. in length, and 3 cm. in width. 

 Another (var. plana) taken from a turtle brought from the Illinois River 

 measures 5.5 cm. in length, 2.3 cm. in width. A living specimen (var. plana) 

 taken from a snapping turtle (Chelydra serpentina) captured near Cambridge, 

 Mass., measures at rest 5.8 cm. in length, 2.1 cm. in width. Whitman says 

 further : " Length in extension, 8.5 cm. ; width, 1.8 cm." My living Cambridge 

 specimen attains in extension a length of about 7.5 cm., in which condition its 

 greatest width is 1.5 to 1.7 cm. 



b. Rings and Somites. 



The rings are distinct except at either end of the body. The furrow between 

 tlie anterior and middle rings of each somite is, however, less deep than that 

 which separates other rings, for which reason the anterior two thirds of a so- 

 mite sometimes appears like a single broad annulus, especially at the margin 

 of the body (Figures 2, 3 b, Plate 1 ; Figure 6, Plate 2 ; Figures 32, 33, 37, 

 Plate 8). 



Somites i., ii., and xxv.-xxvii. uniannulate (Figures 6, 33, 37), but xxv. and 



