186 A MANUAL OF AMERICAN LANH SHELLS. 



foot but two thirds leugtli of shell, whitish ; the body, disk, and mantle 



are marked with white dots; the edge of the mantle is of the same color 



„ ,„, as the head and eye-peduncles. The disk is rounded 



Fig. 184. "^ '^ 



posteriorly and broad and truncated anteriorly ; the 

 lateral borders are deeply crenulated. The head is 

 separate from the disk, as in the Pupa, bearing two 

 Animal ofA.harpa. minutely crcnulated lappets, which hang down on eith( r 

 side of the mouth like a visor, reminding one of the oblique folds on the 

 head of Glandina truncata, whicli we believe to be homologous to them. 

 A longitudinal furrow extends from the mouth downward. The body is 

 so translucent that when extended the ganglionic centers can be plainly 

 seen. In motion it is exceedingly graceful, at times poising its beauti- 

 ful shell high above its body and twirling it around not unlike the 

 Physa, again hugging its pretty harp close to its body. The shell, when 

 in this last position, continually oscillates, as if the animal could not 

 balance it. It rarely ever moves in a straight line, but is always turn- 

 ing and whisking abont, and this is done at times very quickly and 

 abruptly. (Morse.) 

 Jaw and lingual membrane : (see p. 184.) 

 The species is said by Mr. Morse to be viviparous. 



PATUJLA. (See below.) 



Patula asteriscus, Morse. 



Shell widely umbilicated, orbicularly depressed, light brown, decus- 

 sated by delicate incremental and revolving strite and 

 Fig. 185. 



with from 25 to 30 delicate, thin, transparent, i^romi- 



nent ribs, with waving edges and inclined backwards, 

 more like the epidermis than the texture of the shell ; 

 whorls 4, the upper ones flattened, the last globose; 

 suture deeply impressed ; aperture subcircular; peris- 

 tome simple, acute, its columellar extremity subreflected. 

 Greater diameter, li""" ; height, ^™'". 



Helix asierisciis, Morse, Proc. Bost. Soc, vi, 128 (IBS?). — W. G. 



BixNEY, Terr. Moll, iv, 103, pi. Ixxviii, fig. 9; L. & Fr.-W. 



Sh., 1., 82, fig. 145 (1869).— Bland, Ami. N. Y. Lye, viii, 163, fig. 8— Morse, 



Amer. Nat., i, 54G, fig. 43 (1867). — Gould aud Binney, Iuv. of Mass., ed. 2, 415 



(1870). 



Planogyra asieriscus, MoRSK, Joiini. Portl. Soc, i, 24, figs. 50-52, pi. ii,fig. 5; pi, 



viii, fig. .^)3 (1864).— Tr YON, Am. Joura. CoDch., ii, 263 (1866). 

 Patula asteriscus, W. G. Binney, Terr. Moll., v. 167. 



