276 
Platybde I la Anarrl i icl lae 
Suckers. The anterior sucker is cupulilorm and distinct from the 
body, having the mouth at its centre. Here I should like to emphasize 
the difference between this type and that described as hood-like, as 
in Calliobdella. The anterior sucker is scarcely as broad as the body 
at its broadest part. The posterior sucker is also cupuliform and twice 
as broad as the oral (or anterior) sucker. The margins of both suckers 
are entire. In a certain percentage of my specimens, and in those of 
others, the margin of the anterior sucker appears crenated as I have 
shown in Fig. 8; this, however, I am certain is a post-mortem effect 
and does not constitute a specifically different feature (vide Diesing 
1858). The posterior sucker is folded under the abdomen. Both 
suckers are whiter than the rest of the body. Fig. 8 c represents a 
very life-like position. 
Segmentation and Annulation. The skin appears to the unaided 
eye perfectly smooth. Under the microscope the annuli appear to be 
verv numerous and very small. There is great difficulty in counting 
the annuli and deciding how many constitute a segment. We do not 
know how many annuli compose a typical or abdominal segment. 
The animal may, however, be divided into the usual regions as follows, 
the number of segments and annuli being stated tentatively. The 
notation is given in Fig. 1. 
a. Anterior sucker. 
b. Three small annuli, occupying the same situation as similar 
ones in Calliobdella lophii. 
c. The Preclitellum. It is difficult to tell here which are complete 
annuli, and which are subdivisions by chorisis, either complete, or only 
extending partially across the annulus. There appear to be 11 annuli, 
all of which, except the first few, are subdivided, perhaps completely, 
but more probably only partially and superficially by chorisis. (If 
there are 11 annuli it is a coincidence that this region comprises the 
same number as in Calliobdella■ lophii.) 
d. The Clitellum consisting of 3 segments. The first two are 
large, the third small. The first and second segments bear the male and 
female genital apertures respectively. The clitellum is divided from the 
abdomen by a marked line which appears dark and distinct under the 
microscope when viewed by transmitted light, in a preparation cleared 
in oil of cloves. Whereas there is a slight constriction in a mounted 
specimen, there is no noticeable cincture or differentiation in the living 
leech. 
