168 



ZOO LOG 1" 



tia) heros. 

 nat. size. 

 W. H. C. P. 



(Luna- 

 Two-thii-ds 

 Photo, by 



shore-line. Besides littorea there are two species of 



Littorina which were on our coast when records first 



began to be made. The species 



may be distinguished by the circum- ^fT~* 



stances that L. littorea has a black 



head and a heavy shell of brown or 



olive color. L. rudis 1 is smaller, has 



an angle at the apex of 60 to 70, 



and its shell varies in color from 



white to red. L. palliata* has an FIG. ISG. - 



apical angle of 95, and a shell 



varying from white to orange, slate, 



or brown. 



Natica is another common species with an entire mouth. 



It can be at once distinguished from Littorina by the 

 " umbilicus," or depression situated at 

 the left of the mouth and in the axis of 

 the shell (Fig. 156). In the living 

 animal the shell is often quite envel- 

 oped by the large fleshy foot. The 

 members of this genus lay their eggs 

 in spiral " collars " made of aggluti- 

 nated sand. These are common objects 

 of the seashore. 



Fulgur 3 is a good example of a 

 prosobranch having a canaliculated 

 shell. The canal exists for the pur- 



FIG. 157. Shell of Ful- , . . , , . , 



f/ur (Sycotypus) cam- P ose oi containing the siphon by 

 culatus, one of the w hi c h water is brought to the animal 



Fasiolaridse. One- . . ? 



fourth nat. size. Photo. &$ it lies buried in the sand. Inilgur 

 by w. H. c. P. j s our l ar g e st common gastropod. Its 



Rough, rude. 



2 A cloak. 



Lightning. 



