448 Zoological Society. 



stead of being bent downwards, are slightly recurved*. In the co- 

 louring there are also points of distinction: in lieu of the dull brown 

 tint on the top of the head and back, the present species possesses 

 rich rufous brown feathers. In one specimen the body is yellowish 

 white beneath, but in the other it is pure white. 



Mr. Waterhouse then proceeded to make some observations upon 

 a series of skulls of Rodents which were upon the table. These 

 skulls belonged chiefly to species of the various genera contained in 

 the families Chinchillidce (consisting of the genera Chinchilla, Lagotis, 

 and Lagostomus), and Caviidce — composed of the genera Cavia, Ke- 

 rodon, Dolichotis, and Hydrochoerus. Numerous points of resem- 

 blance between these two families were dwelt upon, more particu- 

 larly in the structure of the teeth, the form of the palate, the con- 

 tracted glenoid cavity, the form of the lower jaw, and direction of 

 the lower pair of incisors. The Caviidce, however, possess certain 

 characters, independent of those observable in the form of the teeth, 

 which renders it easy to distinguish them from the Chinchillidce. He 

 alluded especially to the shortness of the condyloid process of the 

 lower jaw, the forward position of the coronoid process, the peculiar 

 projecting ridge on the outer side of the horizontal ramus, and the 

 form of the descending ramus or angle of the jaw ; this projects con- 

 siderably beyond the line of the coronoid process, whereas in the 

 Chinchillidce it terminates in a line with the posterior portion of the 

 coronoid process, or projects but slightly beyond that line. 



Among the Chinchillidce, the Lagostomus trichodactylus, observes 

 Mr. Waterhouse, approaches most nearly to the Cavies, the angle 

 of the lower jaw being less acute and the coronoid process more for- 

 ward than in the other species. 



In the imperfect state of the palate, the narrowness of the ante- 

 rior and posterior sphenoids, the form of the occipital condyles, the 

 form of the articular portion of the lower jaw, and the almost hori- 

 zontal direction of the incisors of the lower jaw of the Chinchillas 

 and Cavies, Mr. Waterhouse stated he had found characters which 

 induced him to place those animals next before the Leporidce. 



May 14. Mr. Cunningham's account of the Apteryx, and Mr. 

 Hope's Monograph of Euchlora, have been inserted above, pp. 3 1 2.342. 



May 28.— WiUiam Ogilby, Esq. in the Chair. 

 A paper from the Rev. R. T. Lowe was read, entitled " A Supple- 

 ment to the Synopsis of the Fishes of Madeira," inserted above, p. 405 . 



* " This difference in the form of the claw cannot be depended on, as the 

 birds have been for some time in confinement; they may originally have 

 been straight, but I think they never could have been curved downwards." 



