PLANORBIS. 493 



Planorhella campannhta, Ciievu, IMan. ilc Concli. ii. 482, fipj. 3559. 



Helix atifjulata, Sheppakd, teste J. de C. Sowerby, Fauna Borcali-Amcrica.na, iii. 315. 



Shell discoidal, yellowish or brownish-green, lighter at the sides ; 

 diameter of its tube nearly twice as great from side to side as in the 

 contrary direction ; right side exhibiting scarcely more 

 than two whorls, which are elevated to an obtuse ridge, 

 and form an nmbilical vortex very nearly perforating the 

 shell ; on the right side are four volutions, distinctly sep- 

 arated by the suture, which are carinated, and form a shal- 

 low, salver-shaped depression ; the whorls enclose each 

 other in a very regular spiral to the last fifth of the outer one, when 

 there is a sudden enlargement and distortion towards the left, by 

 which a large, bell-shaped throat is formed ; ajjerture also dilated, 

 and strongly angular on the left side ; within glazed, reflecting light 

 blue and brown ; surface regularly marked with fine, transverse, 

 raised lines, and intervening grooves. Greatest diameter, half an 

 inch ; at right angles with this, two fifths of an inch ; small diam- 

 eter, one fifth of an inch. 



Found in the larger collections of fresh water, at Fresh Pond, Ja- 

 maica Pond, (fcc. 



It ranges from New England and Nova Scotia through the north- 

 ern tier of States to Minnesota. Fossil in post-pleiocene of Ottawa 

 Valley. 



This shell does not attaiii the size of the preceding species ; and, 

 when mature, its dilated throat distinguishes it from every other 

 known species, and the remarkable manner in which it is turned, 

 as it were by violence, so as to look to the left, is a still further dis- 

 tinction. The outer whorl is everywhere of the same breadth ; and 

 the immature shell, before the dilatation of the throat, may be 

 known by the very regular enrolment of the whorls, and the very 

 contracted aperture in consequence of the very unequal diameters. 



Planorbis hirsutus. 



Fig. 135. 



Shell light yellowish-brown, concave on both sides, most so on the left; whorls 

 three; surface beset with revolving lines of rigid hairs; aperture large, very 

 oblique. 



Plannrhis albm, Muller, Haldemax, Mon. 20, p] 4, figs. 8-10 (1844).— W. G. Bix- 



ney, Smith. Inst. L. and Fr. W. Shells, ii. 132, figs. 219, 220 (ISfio). 

 Planorbis liirsutus, Gould, Am. Journ. Sc. [i], xxxviii. 196 (1840) ; Inv. of ]\Iass. 206, 



