19 



neglect of supplying to the air a sufficient quantity of simple and 

 innoxious moisture is attended with two evils. Not only are the 

 animals kept in an atmosphere too dry for their healthy preserva- 

 tion ; but the dry air, greedily absorbing moisture, becomes impreg- 

 nated with the excreted fluids of the animals in confinement ; and 

 thus the secreting surfaces of the lungs are at once exposed to a 

 constant stimulus from increased and rapid exhalation, and to the 

 additional stimulus inflicted by the continual breathing of air loaded 

 with saline and irritating particles. In well- constructed houses it 

 is of the first importance that the fluids of the animals should be 

 conducted from the buildings. Ventilation should also be perfect 

 not only through the body of the building, but through each indivi- 

 dual cage or den. This is doubly necessary where the air is viti- 

 ated, not only by the animals themselves, but by numerous visitors. 

 For the general regulation of the admission of cold air a convenient 

 plan is to have a leaden or iron weight balanced in a vessel of mer- 

 cury, attached to a sliding sash, which will thus rise or fall in 

 proportion to the height of the mercury. Mr. Cox regards it as of 

 no importance, as to the effect produced on the atmosphere, by 

 what means an increased temperature is preserved, whether by flues 

 or steam or hot water, if the degree obtained be the same : the 

 only reason for preferring one to another is the greater facility it 

 may afford of keeping up an equable temperature. 



Mr. Owen read a portion of his notes made at the dissection of 

 the Beaver which died lately at the Society's Gardens. He limited 

 himself on this occasion to the description of the organs connected 

 with digestion. The salivary organs and those of deglutition were 

 treated of in detail : the former parts, which are remarkably deve- 

 loped in all the Glires, were especially examined on account of the 

 peculiar nature of the animal's food ; while the latter claimed par- 

 ticular attention from the recent interesting discovery by Mr. Mor- 

 gan of a peculiar construction of the fauces in the Capybara, and 

 some others of the Rodent order. 



Of the salivary glands the parotid are the largest. They are 

 united, like the lateral lobes of the thyroid gland in man, by an 

 anterior transverse portion ; and form together a conglomerate 

 mass which extends across the front of the neck to within a short 

 distance of the upper part of the sternum, covering the larynx and 

 its muscles, and passing backwards on each side as far as the mas- 

 toid process. There are, however, two ducts, one on each side, 

 which terminate in front of the molar teeth. The submaxillary glands 

 are quite distinct from the parotid, and are each about the size of a 

 walnut : their ducts pass under the jaw and terminate at the side of 

 the franum iinguce. The sublingual glands are very small. 



Between the membrane of the palate and the bone, in the narrow 

 space between the rows of molar teeth, a layer of mucous glands is 

 situated : and a thick stratum of the same kind of glands exists also 

 immediately exterior to the membrane of the fauces. 



The soft palate extends backwards from the posterior edge of the 



