168 



ZOOLOGY 



tia) her os. 

 nat. size. 

 W. H. C. P. 



Two-thirds 

 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- 

 stances that L. littorea has a black 

 head and a heavy shell of brown or 

 olive color. L. rudis l is smaller, has 

 an angle at the apex of 60 to 70, 

 and its shell varies in color from 

 white to red. L. palliata 2 has an FlG m .- Natica (Luna- 

 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- 



r (Sycotypus) cani- P ose of containing the siphon ^ by 

 culatus, one of the which water is brought to the animal 



Fasiolaridse. One- ,. . -. . -, T ^ , 



fourth nat. size. Photo, as it lies buried in the sand, bulgur 

 by w. H. c. P. i s OU1 . largest common gastropod. Its 



1 Hough, rude, 2 A cloak. 3 Lightning-. 



FIG. 157. Shell of Ful- 



