REPORT ON THE PTEROPODA. 
19 
muscle into the shell, instead of being in the centre of the posterior truncation, is in its 
right hand angle. 
The Digestive Tract . — The anterior portion (buccal mass, oesophagus) resembles that 
of the other Cavoliniidae already examined. The stomach, like that of Clio, possesses 
a fifth large triangular masticatory plate, situated behind the four others, and on the 
ventral side. 
All the species of Cavolinia have a posterior gastric caecum, such as lias already been 
described in some species of Clio. 
The liver in the typical Cavolinise is like that of the preceding genus in shape, and 
its duct opens at the right side of the hinder portion of the stomach. In the group A 
(Carolina trispinosa and Cavolinia quaclriclentata, PI. III. fig. 3) this organ has an 
arrangement unique among the Thecosomata ; it is composed of two lobes, quite separated, 
and having each its own duct. These two lobes of the liver are placed to the right and 
left of the stomach, and their ducts open separately on either side of the gastric caecum, 
the duct of the right lobe being much longer than that of the left. 
In all CaA'olinise the anus opens almost dorsally, quite behind the liver. Close to the 
anus is a flattened anal gland, as in other members of the family. 
The Circulatory and Excretory Organs . — The heart is situated on the right beside 
the genital gland. The kidney is towards the ventral aspect of the latter and behind 
it, disposed almost transversely. In Cavolinia the kidney is not at all spongy ; its 
structure is the same as that found in other Cavoliniidae. 
In all the typical Cavolinise (i.e., the six species included in group B) there is a gill, as 
Boas 1 has already pointed out. In Cavolinia injlexa it is smaller than in the other forms. 
The form and structure of this organ are well known, since Souleyet described and 
figured it in Cavolinia tridentata. I will only remark that the gill of Cavolinia is not 
symmetrical, as might be imagined. The right hand portion is more developed than the 
left, for it extends farther forwards, besides -which it is more dorsal in position. It 
corresponds to the anterior part of the gill in the Gastropoda. 
The Generative Organs . — A consideration of the generative organs as a whole shows 
that some differences exist between the typical Cavoliniidae and the two species included 
in group A. 
In the latter the genital gland is quite ventral in position, and it is developed equally 
on the right and left sides. In the typical Cavolinise, on the other hand, the gland is 
quite asymmetrical, and largely developed on the left side. 
The genital duct in group A presents an elongated swelling on its course, which is 
lacking in the typical forms ; these, however, are provided with a vesicula seminalis 
which has the form of a long caecum, without any dilatation at its extremity, and coiled 
several times upon itself (PI. III. fig. 2, h). Cavolinia injlexa has an ovoid vesicula 
1 Spolia atlantica, p. 207. 
