PACIFIC COAKT SPECIES. 100 



"The Mexican geuus Xanthonyx is uo doubt identical with Binneya, but 

 it does not appear from the figures of alcoholic specimens given by 

 Messrs. Fischer and Crosse (Moll. Mex. et Gnat.) that the mantle of 

 Xanthonyx is extended anteriorly, and the position given by them of 

 the respiratory orifice is different. Should future study of the living 

 animal prove my opinion correct, Xanthonyx will be considered as a 

 synonyme. 



Dr. Pfeifter (Mon. Hel. Viv., VII, 4) suggests the indeutity of Bin- 

 neya with Baudebardia, ignoring entirely the distinction of the first 

 divisions now recognized among the Geophila of presence or absence of 

 a jaw, or of aculeate or quadrate teeth. By the modern arrangement 

 these two genera are most widely separated. 



The surface of the animal is dirty white, with about seventeen verti- 

 cal rows, on each side, of dark blue or slajte blotches, interrupted by 

 the longitudinal reticulations running parallel to the foot, but again 

 commencing and extending to the edge of the foot. These blotches di- 

 verge in all directions from under the shell and mantle, running almost 

 perpendicularly on the side of the animal, but very obliquely in front 

 and behind. The tail is quite keeled with oblique blotches. These 

 blotches also run obliquely from a median line on the forepart of the 

 extended animal. Tentacles, eye-peduncles, and front of head slate 

 color. Lips developed and kept constantly in motion as tentacles. 

 The reticulations of the surface are large and few. In specimens pre- 

 served in alcohol there appears a locomotive disk. Theie is no caudal 

 pore. The respiratory and anal orifices are far behind the center of 

 the mantle edge on the right of the animal. The genital orifice appears 

 somewhat behind the right eye-peduncle. The mantle is scarcely re- 

 flected upon the shell, even in front. When the animal is fully ex- 

 tended, Dr. Cooper says the mantle equals one-fourth of its length. 

 The mantle exudes mucus freely. It seems fixed to the shell, not chang- 

 ing its position with the movement of the animal. 



One of the shells collected by Mr. Hemphill is twice as large as that 

 whose measurements are given above. 



The jaw is thick, slightly arcuate, ends blunt; anterior surface with 

 six well-developed ribs deuticulating either margin, situated on the 

 central third of the jaw, and as many subobsolete ribs on each outer 

 third; no median projection (Fig. 73). . 



Lingual membrane (Plate V, Fig. K, of Terr. Moll., V), long and nar- 

 row. Teeth 31-1-31, with about lo laterals, but the change int* tnar^i- 



