62 THE NAUTILUS. 



NEW AMEKICAN LYMNAEAS. II. 



HY FRANK COLLINS BAKER. 



Lymnaea decollata oronoensis var. nov. 



Shell very globose, inflated, solid ; whorls 3-3^, very convex, the 

 last almost globular ; spire broadly conic, depressed, sutures a little 

 impressed ; aperture roundly ovate, the upper part shouldered two- 

 thirds the length the entire shell; columella with a distinct plait; 

 umbilicus very narrowly open ; color a rich greenish horn, inclinin"- 

 to black in some specimens. The spire is frequently decollated. 



Length 17,00; width 11.50; aperture length 11.00; width 7.00 

 mill. 



Length 16.00; width 10.00; aperture length 10.00; width 6.00 

 mill. 



Length 17.00; width 12.00 ; aperture length 12.00; width 8.00 

 mill. 



Length 12.00 ; width 9.00 ; aperture length 8.7o ; width 5. .50 

 mill, (half grown). 



Distribution: Orono, Maine. (Collection of Mr. Bryant Walker.) 



This variety may be distinguished from decollata by its larger 

 size, more globose form of whorls and the whole shell, and (he 

 rounded aperture shouldered at the upper part. The young or half- 

 grown shell somewhat resembles young individuals of mighelsi and 

 catascopium. 



Haldeman's figure 3 on plate 14 of his monogra|)h seems to repre- 

 sent a form of this variety. It appears to be (piite a characteristic 

 variety. 



Judging from specimens received by Mr. Bryant Walker from 

 Mighels and examined by the- writer, decollata has been figured 

 accurately only by Haldeman in his monograph, plate 14, figs. 1, 2. 

 The species has not been understood by most American collectors, 

 specimens of emarginata, catascopium and migtiehi having been re- 

 ceived as decollata. It is, however, a very characteristic species, 

 not closely connected with any other form. The variety oronoensis 

 resembles some young forms of mighelsi as well as some varieties of 

 catascopium. This resemblance, however, is merely superficial. 



The typical decollata received from Mighels measure as follows : 



Length 12.00 ; width 8.00 ; aperture length 9.00 ; width 5.50 mill. 



