381 Royal Sociclj/. 



blue colour. The tcmpevaturc of the bottom of the lake was y^ of 

 the centigrade scale, at the middle 9°, at the surface 11°; that of 

 the air varying from 14° to 15°. There was no indication of any 

 current on the surface. A cascade 9r)4 feet in height falls into 

 the lake, carrying down the detritus of the surrounding rocks. 



5. " Observations on the anatomy and habits of Marine Testaceous 

 Mollusca, illustrative of their mode of feeding," by Edward Oslei", 

 Esq. Communicated by L. W. Dillvvyn, Esq. F.R.S. 



The author observes that in studying the physiology of the Mol- 

 lusca, more satisfactory results may generally be obtained by tracing 

 the organization connected with each important function, through 

 different families, than by complete dissections of individual species ; 

 and, by thus connecting the study of function with that of structure, 

 the zoologist is led to more certain inferences relating to those habits, 

 the knowledge of which the pelagic character of the animal, and the 

 difficulty of direct observation, would otherwise have rendered unat- 

 tainable. The present paper is devoted to the anatomical investiga- 

 tion of the organs by which the food is received into the bodies of 

 certain Mollusca. The herbivorous Mollusca which the author has 

 examined have three modes of feeding. Some, as the Troclmscrnssus, 

 browse with opposite horizontal jaws : others, as the Turbo L'lttoreus, 

 rasp their food with an armed tongue stretched over an elastic and 

 moveable support: while others again, as the Patella vulgata, gorge 

 it entire. The author enters into a minute anatomical description of 

 the organs of manducation and deglutition, and also of that part of 

 the nervous system situated in the neighbourhood ofthe.se organs, in 

 each of these respective Mollusca, — illustrated by numerous draw- 

 ings. He gives in each case a particular account of the mode of 

 dissection, with a view to direct succeeding observers to obtain a 

 distinct view of the parts he describes, and to verify the conclusions 

 he has himself obtained. 



He next notices a considerable modification in the structure of 

 these organs which is presented in the Chiton. In this animal he 

 finds a pair of simple lateral jaws, rather membranous tlian cartila- 

 ginous. Another variety of structure adapted for gorging food is 

 met with in the Patella mammillaris, where there is simply a very 

 muscular mouth and pharynx, but neither cartilage, tongue, nor 

 hard part of any kind. 



The apparatus by which the Biiccinum Lap'illus drills through shells 

 in order to obtain its food, and the process it employs for that pur- 

 pose, are next investigated ; and that of the Buccinutn undatum is 

 particularly examined with the same view, the structure of the latter 

 being very fully displayed. 



The author hopes to be enabled to pursue these inquiries with 

 respect to other tribes of Mollusca at some future period. 



6. " On the Mammary Glands of the Ornithorhijnclius paradoxus," 

 by Richard Owen, Esq. Communicated by J. H . Green, Esq. F.R.S. 



The author premises a history of the different opinions that have 

 been entertained with respect to the anatomy and economy of this 

 singular animal, which was first described and figured by Dr. Shaw 



