410 THK CHICAGO ACADEMY OF SCIEN'CES. 



sl*ghtly twisted. There is generally a marked rest varix about midway 

 of the body whorl, and in some specimens as many as five of these va- 

 rices may be counted ; in many individuals the lower part of the aperture 

 becomes twisted to such an extent that it spreads far beyond the um- 

 bilical opening; axis twisted and slightly plicate. The juvenile shells 

 are very globose, the strongly shouldered whorls appearing only in 

 nearly adult or old individuals. 



Length. 



Breadth. 



Aperture length. 



Breadth. 





20.00 





12.50 





mill. 



Say. 



19.50 



11.50 



11.00 



5.75 





Autotypes. 



19.10 



10.50 



10.75 



6.00 







21.50 



13.10 



11.75 



8.00 



•• 



Maine. 



22.75 



13.00 



1.5.00 



7.50 



•• 



•• 



28.00 



18.00 



18.50 



10.50 



•• 



" 



27.75 



19.00 



19.00 



10.50 



•• 





30.00 



21.00 



21.00 



11.50 







24.00 



12.50 



13.50 



7.30 





Lake Superior. 



22.00 



12.50 



12.50 



7.00 



'•' 



Isle Royale. 



18.50 



12.00 



12.00 



6.50 



" 



u 



Types : Xot in existence ; autotypes, from Saratoga Lake, three 

 specimens, Philadelphia Academy of Sciences, Xo. 58463 ; Haldeman's 

 serratus, Philadelphia Academy of Sciences, two specimens, Xo. 58470. 



Type Locality: Lakes of Maine ( emarginata ) ; Xorthwest Ter- 

 ritory (serratus). 



Animal: Color generally blackish or bluish-black, head, tentacles 

 and the greater part of the body flecked with white or yellowish white, 

 giving the surface the appearance of being covered with a superficial 

 bloom when the animal is in motion, as described by Dr. Whitfield for 

 Bulimnea mcgasoma} Foot broadly rounded before, more acutely be- 

 hind, very broad and much flattened on the margins ; color bluish-black, 

 lighter beneath and where it joins the body, flecked with yellowish 

 white spots; the center of the sole is lighter than the edge. Head 

 and velum rather short, ranging from semi-circular to very wide in 

 form, with the lateral ends obtusely pointed, according as the animal is 

 motionless or rapidly progressing; the vela area is very large in this 

 species, and frequently assumes a bilobate form anteriorly. Mantle 

 large and conspicuous, fitting closely to the aperture of the shell, blu- 

 ish-black, flecked with whitish or yellowish. Tentacles broad, flat, 

 thin, triangular and very large and conspicuous, obtusely pointed at 

 their extremity, blackish flecked with yellowish white. Eyes black, 

 surrounded by a yellowish-white zone, placed on rather large swellings 

 at the inner base of the tentacles. Respiratory orifice placed near 



1 ~Bu\\. Amer. Mus. Nat. Hist.. Vol. I. p. 30, 1881. 



