34 MR. T. H. HUXLEY ON THE MORPHOLOGY OF THE CEPHALOUS xMOLLUSCA. 
The smaller portion is like a trifid leaf ; it is placed at the base of the former 
portion, and almost reminds one of the sculptor’s vine-leaf*. 
The Testis is not very easily to be distinguished from the liver, behind which it is 
placed, until the contained spermatozoa are recognized. It occupies about the 
posterior half of the nucleus. There is hardly any proper vas deferens, but the testis 
opens by a very short canal at the base of the penis. 
The Ovarium (o) occupies a position similar to that of the testis (figs. 2 and 3). A 
wide oviduct arises from it about its centre, on the right side, and after making one 
bend passes downwards, and opens close to the base of the metapodium. 
The ovarian ova were oval, about ^dth of an inch in diameter, with a clear, 
delicate, germinal vesicle about -g^dth of an inch in diameter, and a pale, circular, 
clear, but thick-walled vesicular germinal spot about y^^dth of an inch in diameter. 
In the oviduct the ova possessed either an entire granular yelk, in which I could not 
detect any germinal vesicle, or the yelk was broken up into two or moie (but not 
many) spherical or subspherical masses, containing a clear vesicle, the embiyo-cell. 
In some individuals a long tube (figs. 2 and 5), half as long as the body or more, 
depended from the orifice of the oviduct. It was colourless and transparent, and 
appeared as if articulated from its membrane being thrown into regular annular 
folds. 
This egg-tube contained a double series of ova, in which the yelks had undergone 
division into 8 to 15 masses of very variable size. The ova seemed to have become 
more divided the nearer they were to the distal extremity of the tube, but I could 
find none containing a distinct embryo. 
The Nervous System (figs. 6 and 7)— Two three-lobed ganglia, closely applied 
together by their inner edges (fig. 7), are placed between the eyes. Each gives off 
several branches to the parietes and the following important trunks : — 
1. A long branch forwards, which terminates in a small ganglion (/3) placed in the 
angle of union of the cesophagus with the buccal mass, and joined to its fellow by a 
very short commissure beneath the msophagus. From these “buccal ganglia” 
various small nerves are given off forwards to the buccal mass and parts about the 
mouth, and backwards, to the msopbagus. 
2. A large optic nerve {i). 
3. A nerve to the tentacle. 
4. A small nerve from the under surface, which terminates in the auditory sac {j). 
5. A large and long commissural branch which runs backwards and downwards 
past the stomach, to unite with the pedal ganglion of its side. 
The Pedal Ganglia (y) are two large ovoid masses in contact by their inner edges. 
* According to Milne-Edwahds (Sur divers Mollusques, Annates des Sciences, 1842), a perfectly similar 
penis is found in Carinaria. He states, however, that the vas deferens traverses one portion of this organ, which 
is certainly not the case in either Firoloides or Atlanta. 
