120 Proceedings of the Royal Physical Society. 
Species were any eyes observable. Assuming, therefore, that these three 
species had respiratory vesicles which Malm failed to see, we can safely say 
they are synonymous with C. nodulifera. In P. crassicaudata, however, a 
blood-red colour was observed, which is very lurid and arresting in his coloured 
plate. This, however, is only a variation, and would not constitute a 
specifically different feature. 
Fic. 1. TRANSVERSE SECTIONS THROUGH VARIOUS PORTIONS OF THE 
NeEcK OF CALLIOBDELLA NODULIFERA. 
A. Through the pharyngeal region. .6. Through the anterior portion of the clitellum. 
R.M. radial muscles; Z.M. longitudinal muscles; Ph. pharynx ; D.C. dermal cells ; 
P.C. pigment cells; S.D. salivary duct; X. The body wall, containing the layers 
shown in Plate VI., but without the cocoon-gland cells ; St. stomach ; D.S. dorsal sinus ; 
V.S. ventral sinus; D.V. dorsal blood-vessel ; V.V. ventral blood-vessel ; V.D. vas 
deferens ; C.V.D. coiled portion of the vas deferens; D.H. ductus ejaculatorii ; 
P. penis ; .N.G. nerve ganglion. 
ORGANISATION.—The segmentation and the respiratory, digestive and 
reproductive systems are as I have described them for Calliobdella lophiw 
(1914); the cocoon-gland cells as I have described them for Platybdella 
anarrhiche (1916). The bursa and the penis do not in this species attain to 
so great a development in proportion to the size of the body as in @. lophis. 
A large proportion of the preserved leeches have the penis extruded. 
Bopy Watt.—The epidermis consists of a layer of columnar cells 
elongated in a direction at right angles to the long axis of the body, having 
their nuclei, which are large, away from the external border, and a cuticle 
secreted at the free edge. At frequent intervals among these epithelial cells 
are flask-shaped glands, usually known as epithelial glands, which are mucus- 
secreting. They are present in most leeches, eg. Branchellion, Piscicola, 
Cystibranchus, etc., but notably absent in Platybdella. The derma is rich in 
large flattened cells 35-45» in length and half as thick, which do not appear. 
to form a definite layer as in Platybdella, but are scattered as in Branchellion. 
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