123 



shells are marked with cross grooves resembling the grooves on the 

 shell, yet these grooves are only formed by the pressure of the dead 

 animal against tlie shell ; for the specimens of the animal which are 

 found out of the shell, or which are taken out of the shell while re- 

 cent, are always destitute of these grooves, or of the compressed 

 form of the cavity of the shell. That some specimens which he 

 had received from the Cape (of which that now on the table was 

 one), which had been packed on their sides, had the upper side 

 of the animal smooth and rounded, and the lower flat, and curved 

 like the shell on which it was pressed by its own weight ; while a 

 specimen which he had received from the Mediterranean packed 

 erect, with the mouth upwards, so that the animal was equally pressed 

 against each side of the shell, was flattened and curved on each side, 

 lilie the specimen examined by M. Ferussac. 



Mr. Gray also stated that, so far from the animal using the finned 

 arms as sails, they were the means by which it retained itself in the 

 shell ; and he further observed, that it was very difficult to distin- 

 guish the species of Argonauta, as they varied greatly in shape, and 

 that on a comparison of many specimens, he had found that the 

 presence or absence of the spines or ears at the back of the mouth 

 were of no importace as a specific character, specimens of each of 

 the recorded species having this process developed only on one or the 

 other side. 



The Chairman, after premising some observations on the diseases 

 to which the mortality of the larger feline animals in the Society's 

 Menagerie was attributable, proceeded to read the followdng descrip- 

 tion of two Entozoa infesting the stomach of the Tiger, (Felis Tif/ris, 

 Linn.,) one of which forms the type of a new genus of Nematoidea. 



" I received a few days ago, from the Medical Superintendent of 

 the Society's Menagerie, a portion of the stomach of a young Tiger 

 (which died of rupture of the aorta), exhibiting on the internal or 

 mucous surface what were considered to be scrofulous tumours. 

 They were five or six in number, of a round and oblong form, vary- 

 ing in size from half an inch to two inches in the largest diameter, 

 and the largest of them projecting about half an inch from the plane 

 of the inner surface : they made no projection externally. The mu- 

 cous membrane covering the smaller tumours was puckered up into 

 minute reticulate ruga: the surface of the largest tumour was smooth. 

 On wiping away the tough thick mucous secretion from the tu- 

 mours, and examining more closely their surface, two or three orifices 

 presented themselves in the larger, and a single orifice in each of the 

 smaller tumours. These orifices conducted to irregular sinuses which 

 were the nidi of two kinds of Nematoid Entozoa, some measuring 

 nearly an inch in length and a line in thickness; the others being 

 more minute, not exceeding 5 lines in length, and about ^L of an 

 inch in diameter. Only a pair of tlie larger Entozoa were found ia 

 each of the three largest tumours ; the smaller species existed in 

 countless numbers. 



" Before proceeding with the description of the worms, I may 



