20 
CHAELES BADHAM. 
to be homologous with the paired vesicles of other Ichthyob- 
dellid leeches. They perform the functions of the side 
vesicles and lateral lacunas of Piscicola-like forms. In place 
of the valve described by Salensky, there are found openings 
guarded by sphincter-muscle fibres. 
The contraction of the dorsal vessel in the testicular region 
is not caused by the lymph flowing back from the lateral 
regions, as described by Johansson (1896 b) for Callob della, 
for here in the segmental lacunas the flow is always to the 
contractile lacunas. It is mainly caused by the flow of lymph 
from behind and partly by the contractility possessed by the 
blood-vessel itself. 
Alimentary System. 
Here I shall employ the terms used by Sukatschoff (1912)' 
in his excellent description of this system in Branchellion. 
The mouth opening is placed slightly towards the dorsal side 
of the anterior sucker and leads into the short pharynx (Text- 
fig*. 6, M.). Following the pharynx is the oesophagus, which 
contains the proboscis characteristic of the Rhychobdellid 
leeches and capable of being protruded by the eversion of the 
pharynx and oesophagus. There follows then the entodermal 
anterior gut. 
The proboscis, when retracted, occupies somites 7, 8, and 9 
(Text-figs. 2 and 6, P.). The proboscis sheath consists of a 
thin ectodermal epithelium covering a number of longitudinal 
muscle fibres. It corresponds very closely to the same 
structure described in Branchellion by Sukatschoff — the 
Text-fig. 6. — Diagram of the Nervous, Alimentary and 
Reproductive Systems of Austrobdella translucens. 
(X 20), A.g. Caeca of anterior entodermal gut. A.m.g. Caeca 
of anterior thin-walled part of middle gut. A. s. Anterior 
sucker. B.g. Blind gut. Ej.t. Terminal part of ejaculatory 
canal. M. Mouth opening. M. g. Caeca of thick-walled part 
of middle gut. M. g.f. Flexure of thick-walled part of middle 
gut, representing a rudimentary pair of caeca. N. gn. 7. Nerve 
ganglion 7, etc. (Fs. (Esophagus. (Fs. gl. (Esophageal glands. 
Ov. Ovary. P. Proboscis. P. gn. Posterior ganglion of 
ventral nerve cord. P. s. Posterior sucker. B. Rectum. 
S. gl. Salivary glands. Sp. gl. Spermatopliore glands. S. gn . 
Suboesopliageal ganglionic mass. T. Testis. 
