96 Zoological Society : — 



glandular bulbs from which hairs might have emanated, but could 

 not discover a single indication of either, nor any recognizable vestige 

 of their obliteration ; — 1 therefore believe the organs for pilous pro- 

 duction were absent, and ab initio. These little animals having been 

 found in a straw-rick, I conclude, will sufficiently indicate their habits 

 and general residence to be similar to those of the common mouse. 



Note. — Having recently heard that a specimen of the same variety 

 of Mus that I have described is preserved in the Museum of the 

 College of Surgeons, I compared it with the examples I possess, and 

 found it precisely the same in every character ; it was caught by 

 the late Mr. Clift in the fire-place of a room in his house in London, 

 and is entered in the Catalogue of Monsters — "No. 121. A common 

 Mouse (Mus Musculus), full-grown, which, from its birth, had not 

 the slightest appearance of hair on its skin, being perfectly naked. 

 Presented by Mr. Clift, 1820." 



Description of the Animals and Teeth of Tylodina and 



OTHER Genera of Gasteropodous Mollusca. 



By Dr. John Edward Gray, F.R.S., V.P.Z.S., P.B.S. etc. 



In the following paper I forward the description of the animal 

 and the teeth of several genera of Mollusca which have not yet been 

 recorded. It is interesting to find that the examination of the teeth 

 justifies the position which was theoretically assumed for the genera 

 in the different families before their teeth were known. 



A. Proboscidifera Hamiglossa. 

 Fam. MuRiciDiE. 



Fusus pallidus (" F. turbinelloides=^Pyrula lignaria, Reeve"). 



The proboscis elongate, cylindrical, subclavate, entirely retractile ; 

 the lingual membrane elongate, narrow, yellow ; teeth in three 

 longitudinal series, 1*1*1, the central transparent, provided with a 

 rounded front edge, armed with three rather elongate, conical, sub- 

 equal denticles ; the lateral teeth yellow, versatile, straight, with two 

 compressed arched processes, the terminal one largest, the basal 

 rather smaller, and with a small tooth on its outer edge. The oper- 

 culum is horny, thick, ovate, subtrigonal, annular, as large as the 

 mouth of the shell ; the apex blunt, rather worn ; the nucleus api- 

 cal, scar large oblong, with a thick callous exterior margin. 



Typhis tetrapterus. 



Operculum horny, ovate, blunt, laminar ; nucleus anterior, apical, 

 as large as the mouth of the shell, rather broader behind. 



PiSANiA ELEGANS. Panama. 



The animal pale brown (in spirits) ; the foot folded up and across 

 behind, and together longitudinally in front, leaving a j^-shaped 

 groove ; tentacles very small ; proboscis elongate, thick, clavate, en- 

 tirely retractile ; lingual membrane elongate, thin ; teeth in three 



