436 MISS LETTICE DIGBY ON THE STRUCTURE OF 
of a single row of plumes (g.’), with blunt rounded ends: 
(Pl. 39. fig. 17), each of which is attached along its dorsal edge, 
and contains a skeletal support continued from the point of 
attachment. Hypobranchial glands are present (q.h., Pl. 39. 
fig. 12). . 
The reproductive aperture (a.g.) (Pl. 39. fig. 12) is a wide. 
oval slit. This, in the female (Pl. 38. fig. 11), leads into a large 
dilated uterus (2.), which is continued to the posterior end of the- 
mantle-cavity, where it is seen to arise from an oviduct (ov.), which 
ramifies in the genital tissue (g.g.). This tissue (Pl. 39. fig. 13)) 
is intimately bound up with the “liver”’ (/.), and with it composes. 
the greater part of the visceral hump. 
There is an accessory gland-like organ (9.g.', Pl. 38. fig. 11): 
closely adhering to the uterus (w.), which protrudes into the- 
mantle-cavity. Its function is unknown, but it may possibly: 
secrete an investment for the eggs. The reproductive organs: 
of the male have not been identified, and it is not known 
whether the accessory gland-like organ is present in the male, or- 
whether Chytra Kirkii is viviparous or not. 
Affinities.—In attempting to define the affinities of Chytra, by 
far the most important feature presented by this genus is the- 
obvious combination of characters distinctive of several well- 
known Prosobranchiate forms. Thus the nervous system is. 
strikingly like that of Capulus (1. pl. 8. fig. 35). So also, when 
viewed from the side, the position and relationships of the pedal, 
pleural, and cerebral ganglia, with their connectives, are very 
similar to those figured by Bouvier for Xenophorus. COhytra may 
be further compared to the Xenophoride in the obviously 
similar character of its shell (4. pp. 307 & 317, pl. 23. 
fig. 6a), and consequently the shape of the body; in the- 
situation of the eyes on the tentacles; in the general character 
of the gill and gill-plumes; in the filiform osphradium; in the 
position of the renal aperture; and in the presence of an 
accessory gland-like organ in relation to the genital apparatus. 
This apparent affinity of Chytra to the Xenophoride is 
perhaps strengthened by a detailed comparison of Chytra Kirkit 
with Aporrhais pes-pelecani (cf. Pl. 39. fig. 18 & Pl. 40. fig. 22). 
In both, there is the same arrangement of the buccal mass, a 
more or less comparable radula (Pl. 39. fig. 20), a very similar 
eill, and hypobranchial glands (9.h., Pl. 40. fig. 22). Further, the 
characters of the nervous system of Aporrhais pes=pelecani 
