. Bulletin - United States National Museum. Science. 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 minutely crcnulated lappets, which hang down on eith( r side of the mouth like a visor, reminding one of the obl
. Bulletin - United States National Museum. Science. 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 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?)
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