GASTEROPODS 



375 



GENUS Cerithidea 



C. scalariformis. This species has the suggestive outlines of the 

 family, but the aperture is simpler. The outer lip is considei'ably thick- 

 ened, sinuous, and yeUow ; there is a very slight notch at the angle 

 of the columella, and the lip serves for an anterior canal. The apex is 

 wanting by reason of the usual truncation of two or three whorls of the 

 spire. There are revolving ribs on the base ; longitudinal ribs elsewhere. 

 The color is a dingy drab ; within, brownish-yellow. It is found in 

 brackish water in Georgia and Florida. This species is said to suspend 

 itself from overhanging vegetation by means of glutinous filaments. It 

 may remain out of water for an almost indefinite time. (Plate LXIX.) 



C. sacrata. A species very common on the mud-flats of San Fran- 

 cisco Bay. It is a high-spired shell of ten heavily ribbed whorls, with a 

 series of revolving ribs on the body-whorl. The outer lip is sinuous, 

 and the columella is slightly twisted. It is nacreous and brown within, 

 dingy blue-black without. Length one inch to an inch and a quarter. 

 (Plate LXIX.) 



FAMILY VERMETIDJE 



GENUS Vermicularia 



V. njnratu. This is a very curious creature 

 when considered from the point of view of the 

 gasteropod mollusk. It seems at first as though 

 it would be better to regard it as a worm which 

 had created for itself a calcareous covering. But 

 it is a true prosobranch notwithstanding the fact 

 that it has departed widely from the conven- 

 tional design in the fashioning of its shell. At 

 first the shell starts out in a regular form, and 

 then the whorls become separated, finally wander- 

 ing about in a seemingly aimless manner. The 

 irregular prolongation sometimes measures ten 

 inches in length. The animal is in no way re- 

 markable except in having the viscera greatly 

 elongated and the foot very short and broad. The 

 color of the animal is light brown with black 

 spots ; the shell-color is rufous or ashy- white. 

 Shells of this genus are often found grouped 

 together in an inextricable mass. It is found 

 in shallow water from New England to Florida. 



FAMILY STROMBIDJE 



Vermicularia spirata. 



This is a particularly interesting family, but it is tropical, and 

 is represented on the shores of the United States by only one 



