34 AMERICAN JOURNAL 



S. testa ovato-conica, tenuicula, vertice sub-oblique acuminato 

 et intorto ; sordide virescente, lineis fuscis irregulariter radiatim 

 filosa, intus nitente castanea. 



Hah. Tristan d'Acunha, Rve. (in error.) Orange Harbor, 

 Tierra del Fuego. U. S. Exploring Expedition. 



External Appearance. The epidermis on the head and sides 

 of the foot is granulose, rough to the touch. The mantle edge 

 is simple, slightly tuberculose and continuous over the head and 

 lobe. The colors, as far as could be judged from the alcoholic 

 specimens, had been purplish. The edge of the mantle was dis- 

 tinctly marked by well defined stripes of dark brown or blackish, 

 and white ; corresponding to the riblets and dark intervals of the 

 shell. The head or muzzle is rounded, with the corners some- 

 what produced or triangular. The sides of the foot are broad, 

 and the sole is smaller in proportion to the aperture of the shell 

 than in most patelliform shells. The lobe beneath the pulmon- 

 ary opening is triangular and large. It is pierced for the anus. 

 On the neck behind the head is a small papilla, indicating the 

 foramen of the genitalia. It is on the right side. The end of 

 the muzzle is flattened, and the mouth is not conspicuous. 



Alimentary System. The buccal mass is proportionately 

 small, and not as muscular as in most pulmonates. The oesopha- 

 gus leaves it irom the middle of the superior surface, and at the 

 posterior end of the buccal body is constricted and bound down 

 by a collar of nerves and muscular fibres. A small elongated 

 salivary gland lies on the upper surface of the buccal mass, on 

 each side of the oesophagus, and empties into it by the posterior 

 termination of the gland. Behind the collar the alimentary 

 canal is broadly dilated, forming a sort of crop. This is slightly 

 constricted, and behind the constriction is the true stomach. 

 This is rhomboidal in shape. The intestine leaves the stomach 

 at its anterior end, on the left side, and is reflected over the 

 latter in a broad loop to the right, when it turns again, and 

 passing around the posterior end of the body opens through the 

 lobe, which closes the pulmonary orifice. Some small muscular 

 fibres bind the posterior end of the stomach to the foot. 



The jaw is horny and dark brown. The cutting edge is 

 smooth and arcuated. The portion which is inserted into the 

 flesh is striated and produced into long, stout, muscular fila- 

 ments, which are not represented in the figure. There are two 

 well marked notches on the superior edge. The jaw is deeply 

 grooved behind and the inner surface striated. 



The radula is stout and of a dark brown color. 



The formula is 50-1-50 or 20-30-1-30-20. 



