CASTLE: NORTH AMERICAN RHYNCHOBDELLID®. Bil 
6. Glossiphonia parasitica Say (1824). 
Plate 1, Figs. 2, 3a, 30; Plate 2, Fig. 6; Plate 8, Figs. 32, 33, 37. 
Hirudo parasitica Say (’24) ; Clepsine parasitica Diesing (’50); C. plana 
Whitman (91°); ? C. chelydra Whitman (’91*). 
a. Hasitat, 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 
Blanchard (°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 em. in width. 
Another (var. plana) taken from a turtle brought from the Illinois River 
measures 5.5 cm. in length, 2.3 em. 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, 8.5cm.; width, 1.8 em.” 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. 
6. Rixes anp Somitss. 
The rings are distinct except at either end of the body. The furrow between 
the 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}, Plate1; Figure 6, Plate 2; Figures 32, 33, 37, 
Plate 8). 
Somites 1, 11., and XXV.-XXVII. uniannulate (Figures 6, 33, 37), but xxv. and 
