No. 3668 PTERODRILUS—HOLT 21 
Remarks.— Unfortunately, much of the material on which the 
description of P. hobbsi is based is poorly preserved since it was col- 
lected by students of crayfishes whose requirements are such that the 
branchiobdellid material in their collections often proves unsuitable 
for careful study or positive identifications. There is no doubt that 
P. hobbsi is a distinct species occupying an extensive range; future 
studies based upon larger series of collections that are better preserved 
may reveal the presence of other and similar species among the animals 
presently assigned to this species (see below, p. 32). 
Pterodrilus cedrus, new species 
Figures 5, 10 
TYPE-SPECIMENS.—Holotype and five paratypes, USNM 36464, 
from Orconectes placidus (Hagen) and Cambarus tenebrosus Hay taken 
in a small stream at the intersection of State Highways 52 and 53 at 
Celina, Clay County, Tenn., by Perry C. and Virgie F. Holt, July 
25, 1961. 
Draenosis.—Dorsal ridges on segments I-VIII, that of VIII 
bearing four short conical projections; bursa subspherical, small, 
reaching ventral border of gut; ejaculatory duct of medium length; 
prostate about % diameter of and equal in length to spermiducal gland, 
differentiated; spermatheca frequently exceeding body diameter in 
length, strap shaped to clavate, ectal duct long. 
ErymMoLoey.—Latin, cedrus, the cedar tree, by extension as a 
common name, the red cedar, Juniperus virginiana, for the cedar 
glades that are such a conspicuous part of the landscape of middle 
Tennessee. 
Description.—Pterodrilus cedrus is a small worm, about 1.0 to 
1.3 mm long; the combination of dorsal ridges on the first eight body 
segments and the four finger-like projections borne on the ridge of 
segment VIII are distinctive. These projections are short and resemble 
closely those of the corresponding segment of P. distichus. 
The spermiducal gland is small, approximately twice its diameter 
in length. The prostate is broadly joined to the spermiducal gland and 
composed of highly vacuolated cells that end abruptly at the level of 
the separation of the two. It extends entally to the ental end of the 
spermiducal gland. The ejaculatory duct is about equal in length to the 
bursa and therefore longer than that of P. mexicanus and perhaps 
somewhat shorter, relative to the size of the organs, than that of P. 
hobbsv. The bursa is much like that of all members of the genus, except 
P. mezxicanus, P. choritonamus, and P. missouriensis, that is, small 
and subspherical in shape. 
313-169—68——4 
