378 NOTES ON .SOMK IIRITISII NUDIBRANCIIS. 



seating the first teeth. The iiuiture teeth (PI. xi., Fig. 25.) are hirge 

 and spoon-shaped. The outline is rather irregular, and there are 

 generally two more or less distinct projections on the back. 



There is no crop attached to the buccal mass, but from it issues a thin 

 tube (Fig. 26. a.) which must apparently l)e regarded as equivalent to a 

 stomach as well as to an oesopliagus, at least in its posterior part, for 

 from it arises the intestine (PI. xii., Fig. 26. b.). This is a larger tube 

 which bends slightly to tlie right and then runs directly backwards at Hrst 

 on the right under the side of the pericardium and finally above the renal 

 organ to the anal papilla (Fig. 26. c). The thin tube issuing from the 

 buccal mass bears two folds inside. At its posterior extremity these 

 folds become more numerous, and the tube bends downwards and dilates 

 into a large stomach-like pouch (Fig. 26. e.). It is clear, however, that 

 the intestine does not issue from this pouch, but from the narrower 

 tube. It is probable that the animal lives on vegetable juices, and that 

 the two folds in the tube act as strainers and valves, establishing com- 

 munication alternately between the mouth and the pouch and between 

 the pouch and the intestine, only one line of communication being open 

 at a time. The pouch is prolonged anteriorly under the oesophagus and 

 divides into two diverticula (Fig. 26. d.) which enter the anterior lobes 

 of the foot. Posteriorly it extends almost to the end of the body and 

 gives off two sets of ramifying diverticula (Fig. 26. f.). The upper 

 diverticula (about four in numl>er) enter the cerata and are also ramified 

 in the body. The lower diverticula (also about four) extend downwards 

 through the hermaphrodite gland and do not enter the cerata, but their 

 ramifications witliin the body create the peculiar dendritic maikings 

 (Fig. 28. i.) visible througli tiie sole of the foot. 



The central nervous system (PI. xi., Fig. 30.) forms a collar round the 

 oesophagus consisting of seven principal ganglia close to one another 

 and connected by very short commissures, the longest being that con- 

 necting the cerebral ganglia. They should probably be regarded as two 

 cerebral, two pedal, and three visceral ganglia. Connected with the 

 cerebral ganglia are two smaller ganglia, probably rhinophorial in 

 function and innervating the most sensitive part of the head, altliough 

 no external rhinophores are developed. 



The hermaphrodite gland is large and ramified throughout the whole 

 lower part of the body, filling up the interstices between the other 

 organs. The ampulla and duct of the gland are short. After the bifur- 

 cation of the male and female branches (PI. xii., Fig. 27. b.) the former 

 runs to an orifice at the right anterior corner of the iiead. The vas 

 deferens (Fig. 27. d.) is not very long or much convoluted. A rather large 

 prostate (Fig. 27. c.) opens into it by several ducts. The penis is armed 

 with a rather long curved siiine which in some specimens at any rate 



