12 A MONOGRAPH OP THE 



and in Bendronotus there are several. In Lomanotus, Antiopa, and Proctonotus, the lateral 

 spines are numerous, the lingual membrane being broad in these genera, as in Boris. Loma- 

 notus has no central spines. Hermcea, Btiliger, and Alderia, also present a peculiar modification 

 of this organ. In them there is a single longitudinal series of plates, as m Eolis; but they are 

 articulated, resembling the vertebrae of the spinal column, and each bears a very large, broad, 

 simple spine. 



In addition to the dentigerous tongue, Boris repanda, B. pilosa, Goniodoris, Idalia, and 

 Ancula, have a spiny, prehensile collar, placed at the entrance of the buccal organ, on what 

 has been denominated the buccal lip. B. coccinea, B. bilamellata, and Euplocamus croceus, 

 are also provided with a similar collar ; but in these the surface of the organ is roughened with 

 papillae or imbricated scales. The genera in which this apparatus is most strongly developed, 

 are characterised by narrowness of tongue and deficiency of jaws. It would therefore seem 

 probable, that the collar is a compensation for diminished prehensile power, consequent upon 

 these circumstances. At least it is rarely associated with a powerful tongue, and never with 

 lateral jaws. There is a narrow belt of spines on the outer surface of the jaws of Tritonia, but 

 this would seem to differ from a prehensile collar. The tongue, in all the Nudibranchs, is more 

 of a prehensile than a rasping instrument : in Eolis the protruded jaws lay hold of its prey, 

 cutting out lump after lump, which the tongue, advancing, seizes by the aid of its recurved 

 spines, and with a backward motion carries to the entrance of the oesophagus. The broad 

 tongue of Boris acts at once in the capacity of both jaws and tongue ; it is hollow or scoop- 

 formed, and, on being applied to the surface of its food is flattened out ; the sides then collapse, 

 when the spines laying hold, a piece is torn or licked out, as it were, and brought immediately 

 to the back of the mouth by the withdrawal of the tongue. The tongue in Tritonia must act 

 much in the same way, but here, probably from the different nature of its food, it requires the 

 assistance of a pair of powerful jaws. In most of the species with a prehensile collar, the 

 lingual organ is narrow, has lost the scoop-like character, and is functionally very similar to 

 that of Eolis. The collar, in these forms, will seize the prey somewhat in the manner of jaws ; 

 then the tongue will be advanced, and do its work of carrying the food to the oesophagus. 



The oesophagus, stomach, and intestine are well marked ; the former is generally short 

 and passes from the upper surface of the buccal mass. In the Boridida, and in a portion 

 of the Tritoniadce, there is a pair of well-developed salivary glands, pouring their secretion into 

 the buccal cavity, one on each side of the oesophagus. The Eolididce* appear to be devoid of 

 these organs, with the exception of Tethys, a very abnormal genus, in which they are quite 

 rudimentary. 



The stomach varies considerably in size and form ; and, in the Borididce, is frequently 

 buried in the liver. In them, too, there is occasionally, besides the buccal gizzard already 



* We have described Doio as possessing salivary glands, in the account of that genus. A more 

 extended knowledge of the anatomy of these animals has, however, induced us to change our opinion 

 respecting the nature of these organs, which we are now disposed to look upon as glands for secreting 

 mucus to lubricate the foot, similar to those for the like purpose pointed out in Fiona. The salivary 

 glands of Calliopcea (Stiliger) described by M. Souleyet, will probably prove to be of the same nature. 

 The minute salivary glands described under the head Eolis, we are now satisfied do not exist. We 

 were deceived in our original examination by the lodgment of extraneous matter between the jaws and 

 the fleshy walls of the mouth. 



