ORGANS OP SECRETION. 591 



glands, commonly one or two pairs, disposed along the sides 

 of the oesophagus, and opening by long ducts into the mouth, 

 consist sometimes of simple single elongated tubuli, as in 

 bullosa, aplysia, and other genera, sometimes of racemose 

 clusters of follicles, forming a compact lobulated organ, as in 

 ariorii buccinum, and many others, and sometimes these two 

 forms occur together as in the doris. The liver, as in other 

 mollusca, is of great size, consisting of numerous aggregated 

 lobes, composed of small short tubuli filled with their biliary 

 secretion, surrounding the greater part of the stomach and 

 intestine, and opening by one or more oblique, wide orifices, 

 into the pyloric end of the gastric cavity. The pancreas 

 consists of a small single glandular coecum, with thick folli- 

 cular parietes, opening by a wide distinct orifice into the 

 cavity of the stomach, close to the openings of the hepatic 

 ducts, as in the doris and aplysia. The urinary glands are 

 found to contain uric acid, as in conchifera, they consist 

 generally of a conglomerate mass of small follicles, with a 

 single efferent duct or ureter which opens externally near 

 the anus, as in arion, umbrella, pleurobranchus, doris, 

 aplysia, and other genera, and sometimes a small vesicle, 

 or urinary bladder, is developed in the course of the ureter. 

 These have also been regarded as calcifient glands. 



Both in the naked and testaceous gasteropods, there are nu- 

 merous muciparous follicles disposed on the surface of the 

 body, to lubricate and protect the skin. In the testaceous 

 pectini-branchiale tribes, there are often considerable mucipa- 

 rous glands disposed under the mantle to lubricate the interior 

 of the pallial and respiratory cavities, and to protect them from 

 the irritation of excrementitious and foreign matters. Many 

 species present also at tno bottom or near the margin of the 

 pallial cavity, soft follicuiar glands destined to afford secre- 

 tions of various and often lively colours, as the blue of the 

 janthinte, the yellow of the bulla, and the purple of the mu- 

 rices. Thejantkina and the glaucus appear to derive their 

 deep blue colouring matter, from feeding on the deep blue 

 velellae, which float with them near the surface of the sea. 

 Chiaje found the purple secretion of the myrex tritonis to be 

 produced by the parietes of a glandular sac, situate at the 

 bottom of the pallial cavity, and communicating with that 

 cavity by a small foramen. The float of the janthina, by 



