274 
MR. R. OWEN ON THE ANATOMY OF CLAVAGELLA. 
The same letters indicate the same parts in each figure. 
i) 
. Anterior wall of the chamber. 
. Dorsal wall. The letter is placed on the hinge of the fixed valve. 
. Ventral wall. 
. Posterior or siphonic outlet. 
. Tubular communications with a neighbouring cavity, here sent off from 
the posterior part of the mantle. 
. Calcareous tubes secreted by the above processes and extending into the 
cavities contiguous to the throat of the tube. 
. A cavity communicating with the anterior part of the chamber. 
. Impression of the posterior adductor muscle. 
. Impression of the anterior adductor muscle. 
. Impression of the pallial muscle, or third adductor. 
. Posterior or large adductor. (The single adductor of the Ostracea, &c. 
corresponds to this. The following are superadded in other families 
of Bivalves.) 
. The anterior, antero-dorsal, or smaller adductor. 
. The pallial or antero-ventral adductor. 
i. The convex muscular mass continued over the anterior part of the body, 
and reducing the rictus of the mantle to the small slit * , through which 
a bristle is placed in fig. 12. (This mass is an inordinate development 
of what forms the muscular margins of the mantle lobes in other 
Bivalves.) 
. Muscular fibres of the siphon. 
The respiratory, or ingestive, siphonic canal. 
. The anal, or egestive, siphonic canal; m’. (fig. 16.) its valve. (These 
are indicated by bristles in fig. 14.) 
. The labial or buccal appendages. 
. The mouth, exposed by dividing the superior labial process. 
. The esophagus. 
. The stomach, showing the orifices of the hepatic ducts. 
The cecum. 
. The intestine. 
. The anus. 
The gills: in fig. 11 the right gill is seen partially protruded between 
the muscular parts of the mantle. 
. The auricles, wv. the ventricle, of the heart. 
w. The liver surrounding the esophagus, the stomach, and part of the intestine. 
. Part of the ovary. 
. The foot. 
ee 
