1042 > DR. F. E. BEDDARD ON 
and it is not a little unusual to find that: the abundant dorso- 
ventral fibres are of stouter build, and thus much more 
conspicuous in a transverse section. Calcareous bodies are 
numerous in this species, and are to be found throughout the 
body both in the cortex and the medulla. 
The water-vascular system consists of the usual four longi- 
tudinal trunks, of which the ventral are connected by the usual 
transverse vessels in each segment. Both in transverse and 
horizontal sections it can be observed that the two trunks of each 
side of the body are placed as nearly as possible side by side. 
The outermost of the two vessels, however, is slightly to one side, 
that is to say, it is, being the dorsal vessel, slightly dorsal in 
position of the ventral tube. It is well known that the relative 
positions of the dorsal and ventral tubes when lying side by side 
differ, being in some species arranged precisely in the reverse 
fashion to others. In the present worm the dorsal vessel lies to 
the outside, as I presume from the fact that the outer vessel is 
not the one which is connected with its fellow by the transverse 
vessel in each segment, and from the fact that it is from time to 
time much narrower in calibre than the inner ventral vessel. 
Often, however, the two vessels are of the same size. The trans- 
verse tubes lie in the middle of the medulla, and at the end of 
the segment. The inner longitudinal vessel bends inwards to 
give off the transverse vessel, which thus forms a Y-like angle. 
I could discover no trace of any network connected with any of 
the main trunks. Such a network exists in the family Acoleidee, 
and is referred to by Fuhrmann * in Shipleya inermis. 
nd 
Genital Organs. 
A peculiarity of this species—which, however, it shares with 
a good many Cestodes—is the early development of the genital 
organs. It agrees, for instance, with Schizotenia americana (to 
accept v. Janicki’s identification of Stiles’s species tT) in this 
feature, a point which must be borne in mind in comparing the 
two. I recognised in longitudinal horizontal sections consider- 
able traces of the genitalia in the fourth segment, and I would 
not like to assert the absence of still more undifferentiated 
beginnings in an earlier segment. In the sixth segment the 
cirrus-sac was fairly developed and the sperm-duct obvious ; and 
in the sixth segment I saw for the first time a perfectly clear 
circular external pore. This was seen in a specimen mounted 
entire in glycerine, and it agrees with another specimen which 
I examined by sections. There were pores in all the segments 
posterior to the sixth. I have already mentioned the absolute 
regularity of the alternation of the genital pores from right to 
left side. The earliest segment in which the genitalia appeared 
to be quite functional was the ninth, in which J observed the 
* Rey. Suisse Zool. xvi. 1908, p. 70. 
+ Proc. U.S. Nat. Mus. xix. 1897, p. 165. 
