ANATOMY AND PHYSIOLOGY. 
Moll. 35 
glands homologous with the pedal glands of Gastropods ; the so-called 
aquiferous pores are the apertures of these glands, there being no direct 
communication between the circulatory apparatus and the exterior ; 
Bar KOI 8. 
The pericardial gland in Pelecypoda is lobate, and consists of caeca, 
situated anteriorly in the pericardium and developed from its epithelium; 
its degree of development varies considerably. The epithelial cells con- 
tain various concretions. Its function is probably renal, the products 
escaping into the kidney : probably it is homologous with structures 
already described in the Cephalopoda ; Grobben (2). 
7 . Nervous System. 
Some observations on the true nervous and connective elements in the 
central nervous system are described by Haller, in which certain Mol - 
In sea are incidentally referred to. The author comes to the conclusion 
that the central nervous network was originally distributed evenly over 
the whole surface of the body. 
In the nervous system of Gastropods the origin of the cerebro-sympa- 
thetic connectives from the anterior superior surface and the presence of 
two symmetrical ganglia in the angle between the oesophagus and lingual 
pouch are constant phenomena, and these two ganglia form the st.omato- 
gastric centre. Subsidiary ganglia are developed in correlation with 
specially elaborated portions of the digestive tract, but these are not to 
be confused with the stomatogastric centre proper; Lacaze-Duthiers (2). 
The visceral commissure of Prosobranchiata is chiastoneurous : it 
originates in the commissural ganglion, and has a subin testinal branch 
passing backwards from loft to right under the oesophagus and forming 
the subintestinal ganglion. Another branch crosses abovo the intestine, 
forming a supra-intestinal ganglion, and eventually joining the sub- 
intestinal branch ; Bouvier (4). 
There is no proboscidial commissure in the Ctenobranchiata , but there 
is a connective joining the right commissural ganglion with the sub- 
intestinal, and formed by the union of the right pallial nerves, which 
spring from the right commissural, and the sub intestinal ganglia. In the 
Cerithiidce its formation may be traced step by step. In Ampullaria 
the left pallial nerve is converted into a connective ; Bouvier (3). 
The nervous system of Conus has a general resemblance to that of 
Buccinum undatum } both being chiastoneurous ; the cerebral, commis- 
sural, and supra-intestinal ganglia are closely approximated, while the 
pedal and sub-intestinal are at some distance from them on the right 
side of the body. The points of difference are : long sympathetic con- 
nectives, two long sympathetic commissures — the posterior the larger — 
a visceral commissure, with two brandies directed backwards and to the 
left, and bearing three distinct ganglia. The Terebridce have a retractile 
proboscidian sheath, variations in which led Troschel to divide the group 
into five genera ; a step hardly justified, since they agree in having two 
salivary glands united in the middle line ; a double fold of the oesophagus, 
as in Buccinum, in the angle of which lie the nervous centres; the penis and 
siphon well-developed— a purple-gland. The disposition of the nerves is 
characteristic ; each cerebral ganglion sends two strong cords into the 
