LIMN.EA. 



rs 



Fig. 55 gives, at one view, the two forms which I have con- 

 sidered synonymous. 



Fig. 56. 



Fig. 57. 



Lininaea SUlliassi, Baird. — Shell elongate, attenuated, horn- 

 colored, fragile ; whirls six, the last twice the size of the remainder ; 

 aperture moderate ; columella strongly plicate ; external 

 surface with microscopic, crowded, very minute decussa- 

 tions. Length of large.st l^, hreadth ^ inch. 



Hab. Sumass Prairie, Eraser River, British 

 Columbia. 



This species of Limnaea approaches L. elodes, 

 Say, but is more elongated, more fragile, and 

 has the columella very strongly plicated. The 

 surface of the shell, when seen under a lens 

 of moderate power, is finely decussately striated. 

 It is of a horny color, and is of an elongated 

 shape. {Baird.) 



Limnxa humassi, Baied, Proc. Zool. Soc. Lon- 

 don, 1863, p. 68. 



Fig. 58. 



This species was collected by the British Boundary Commission. 

 Members of the American Commission also col- 

 lected the specimens in the Smithsonian collection, 

 which show the species to be extremely variable. 

 I have copied above the original description and 

 two figures from the advance plates of the British 

 Report, kindly furnished by Mr. Carpenter. 



A curious specimen, from Ft. Colville (North- 

 west Boundary Survey), is figured in Fig. 58. It 

 may be referable to this species. 



Cat. No. 



No.ofSp. 



30 



LocaUty. 



E. of Ft. Colville, W.T. 



From vehom recoivPtl. 



N. W. Boundary Surv. 



