TOP - SHELLS. 33 



Cattwstoma canaliculatum, Mart., Grooved 

 Top-shell, Fig. 4, PI. VIII, is upwards of an inch 

 in length and breadth. It is very thin and light, 

 conical in shape, and marked by very strong spi- 

 ral lines alternating with lesser ones, with a dis- 

 tinct suture between the five whorls. Exterior 

 color, light brown ; interior of aperture, brightly 

 iridescent. 



Trochiscus Norrisii, Sby., Fig. 5, PI. VIII, 

 abundant southward, rare at Monterey, is alarge, 

 smooth, brownish shell, with low spire, rounded 

 whorls, very large umbilicus, and ample aperture, 

 which is closed by a mossy, circular operculum. 

 It is found on the rocks, like the Turbans. The 

 The last shell; No. 7, figured on plate VIII, is 

 Leptonyx sanguineus, Linn., alias Leptoihyra 

 sanguined. The figure shows the natural size, 

 though it sometimes grows larger. It is strong 

 and solid, few whorled, marked by regular spiral 

 stride. It may be distinguished from small spec- 

 imens of C. costatum, by its rounded whorls, 

 white interior, and white, shelly operculum. Its 

 color is red or purple. It may be found living 

 on the surface of rocks, at low water. 



t^rr 



