LYMNiEIDJE OF NORTH AMERICA. 223 



Remarks : Sonomtznsis is related to bulimoides. Its distinguish- 

 ing characteristics are its short, dome-shaped spire, globose form and 

 lather rapidly expanding last whorl. The aperture also is somewhat 

 patulous. The columella is narrower and more heavily appressed to 

 the columellar region than in Galba bulimoides cockerelli; the umbilicus 

 is a narrow chink, while in cockerelli it is rather zvidely open. 



This species has been variously referred to ampla Migh., ampla 

 ittahensis Call and to perpolita Dall, but it is not related to any one 

 of these save, perhaps, the last, which seems to be related to bulimoides. 



Galba hendersoni (Baker). Plate XXVIII, figures 15-18. 



Lymncea hendersoni Baker, Nautilus, XXII, p. 140, April, 1909. 



Shell : Globose, very thin and fragile ; periostracum light yellow- 

 ish or brownish horn ; surface dull ; sculpture of fine growth lines, 

 without spiral lines; whorls 3^, very rapidly increasing in diameter, 

 the body whorl seven-eighths the length of the entire shell, very 

 globose ; spire very short, depressed, dome-like, the first two whorls flat 

 and coiled in the same plane, so that a profile view shows only two 

 full whorls. Nuclear whorl flat, partly concealed by the volutions of 

 the spire; sutures impressed; aperture round or roundly elliptical; 

 cuter lip thin; inner lip broad, triangular, reflected over the columellar 

 region, but leaving a deep, well-marked chink; the inner edge of the 

 inner lip is usually bent downward near the body whorl, partly con- 

 cealing the umbilical chink ; parietal callus thin ; axis smooth, hour- 

 glass-shaped. 



Aperture length. Breadth. 



4.75 3.00 mill. Type 



4.00 2.50 " 



4.80 3.00 " 



4.00 2.50 " 



Types : Chicago Academy of Sciences, six specimens, No. 24537 ; 

 cotypes, University of Colorado, Boulder, Colorado. 



Type Locality : West of Fort Collins, Colorado. 



Animal (in alcohol) : With a very broad, short foot, 4.00 by 3.00 

 mill. ; tentacles very large, broadly triangular. The animal seems to 

 be large for the size of the shell. 



Jaw : Resembling that of Galba bulimoides techella. 

 Radula (plate VI. figure P) : Formula : J^+^T+i+T+l+Tf-T+s-T 

 (23-1-23) ; the teeth are similar to those of techella. The marginals 

 begin quite abruptly, the entocone splitting into two acute points on 

 the ninth (second intermediate) and into three points on the tenth 

 (first marginal") tooth. The cusps of the marginal teeth are very long 

 and acute. There are over 110 rows of teeth. 



.ength. 



B 



readth. 



7.00 





5.50 



6.25 





5.00 



6.75 





5.00 



5.50 





4.10 



