102 



PROCEEDINGS OF THE ACADEMY OF 



[Feb., 



The mantle within the last whorl is white, with the anterior vessels 

 of the lung faintly traced in gray and having gray pigment along the 

 periphery. 



Southern forms resembling A. proximo. — Raspberry Gulch. A few 

 specimens in poor condition are intermediate between proximo and 

 fissidens as to the basal teeth, but the umbilicus is much narrower than 

 in either, and the peripheral angulation is less pronounced, thus 

 approaching A. duplicidens. There are over 6 whorls. Other southern 

 localities for forms of A. proximo are Rucker Canyon and "Turtle 

 Head," a station between Crook's Peak and the mouth of Rucker. 



.4. fissidens should by rights be subordinated to proximo, as a sub- 

 species, on account of the various intermediate forms; yet the status 

 of the races can be more clearly expressed by the artificial device of 

 making it a "species." 



Ashmunella proxima emigrans n. subsp. Fi{j. 18. 



On Big Emigrant .Mountain, Big Emigrant Canyon, a race was found 

 having some characters of A. fissidens. The shell Is somewhat larger 



Fig. IS. — A. p. emigrant 



A . ( ', apertures of adult shells. B, young shell 1 1 mm . 

 diam. Big Emigrant Canyon. 



than proximo, more robust, with slightly less than 6 whorls. The 

 two basal teeth are less separated, somewhat united by a callus at 

 their bases, and the inner one is generally smaller, frequently very 

 small. There is often the weak trace of an upper branch, making the 

 parietal tooth V-shaped. Fine spirals may be seen on the base of 

 the shell. The young shell forms a very strong callous rib within the 

 lip, as in A. fissidens. The umbilicus is narrow, contained five times 

 in the diameter of the shell. Alt. 5.8, diam. 13.2 mm. 



This shell is like A. fissidens except in the single character of having 

 the basal teeth more widely separated. As in that species, the inner 

 of the two basal teeth is quite variable in size. It is a race intermediate 

 in character between fissidens and proxima. 



