410 THE CHICAGO ACADEMY OF SCIENCES. 
slightly 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. Aperturelength. | Breadth. 
20.00 bieebs 12.50 usaumill Say: 
19.50 11.50 11.00 5 ee eAUtOLypes. 
19.10 10.50 10.75 6:00): f 
21.50 13.10 eS 8.00 “ Maine. 
22.75 13.00 15.00 Olan: R 
28.00 18.00 18.50 10:50) = x 
27.75 19.00 19.00 1050 oy 
30.00 21.00 21.00 AAL5O}. <* 
24.00 12.50 13.50 Teak) Lake Superior. 
22.00 12.50 12.50 7.00 “ Isle Royale. 
18.50 12.00 12.00 6:50) ss 
Tyres: Not in existence; autotypes, from Saratoga Lake, three 
specimens, Philadelphia Academy of Sciences, No. 58463; Haldeman’s 
serratus, Philadelphia Academy of Sciences, two specimens, No. 58470. 
Type Locauity: Lakes of Maine (emarginata); Northwest 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 megasoma.* 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 
1Bull. Amer. Mus. Nat. Hist., Vol. I, p. 30, 1881. 
