REPORT ON THE PTEROPODA. 
17 
and farther, there do not exist between Clio and Cuvierina any differences in the form 
and disposition of the heart and kidney. 
The Generative Organs . — The genital duct has no vesicula seminalis in its course. The 
accessory genital glands resemble those of Clio, but the genital aperture is characterised 
by the frequent presence of a long flattened appendage, situated on its ventral aspect. 
This organ is narrow at its base, and divides further on into two branches, of which the 
right terminates in a point, whilst the left enlarges as it proceeds, expands into the form 
of a fan, and is truncated at its extremity where it ends in a pad. This appendage, like 
the whole cervical region, is innervated by the pedal ganglion. Its function is not hitherto 
known with certainty. Several naturalists have erroneously taken it for the penis (the 
penis of Cuvierina is situated in the same position as that of other Cavoliniidse, and is 
of the same form) ; but it seems probable that it is an accessory copulatory organ, and 
assists the two individuals in coitu in maintaining their attachment to each other. 
The somewhat frequent absence of this appendage and its variable degree of develop- 
ment lead me to think that it is a temporary organ. 
The Nervous System of Cuvierina is on the whole constituted like that of other 
Cavoliniidse. The cerebral and pedal ganglia resemble those of Clio, and give origin to 
the same nerves. 
The pedal sanoiia show clearlv a small second commissure in front of the first 
(PI. III. fig. 1, e). 
The pleural ganglia, which were discovered in Clio by transverse sections of the 
nervous system, are here recognisable externally, as distinct from the three other ganglia 
of the same side (PI. II. fig. 10, c). 
The visceral ganglia, which in Clio were seen to form a mass, composed of two asym- 
metrical but not separate halves, form here two ganglionic masses, closely approximated 
but still distinct, as in Limacina, with this difference, that the larger ganglion is on the 
left and the smaller on the right. 
The large ganglion corresponds to the larger half of the visceral ganglionic mass 
of Clio ; in fact the same nerves issue from it : the left pallial nerve (PI. III. figs. 1, T), 
and the nerves of the “abdominal ” ganglion (genital, 3, and visceral, 0) ; whilst from 
the right ganglion issues only the right pallial nerve ( 1 ) which also supplies the 
osphradium. 
There are no differences in the form and position of the otocysts and the osphradium 
between Cavolinia and Clio. 
3. Cavolinia. 
It has already been pointed out that this genus consists of two groups : — (A) formed 
by Cavolinia trispinosa and Cavolinia quadridentata ; (B) including the other six species 
(ZOOL. CHALL. EXP. — PART LXVI. — 1888.) Uuu 3 
