THE SLUG 217 



Cold Spring Harbor, near the western end of Long Island Sound, 

 but has since become so. Persons who live on the coast south of 

 New York City would do well to note carefully the abundance of 

 the species on their part of the shore-line. Besides Uttorea 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 

 circumstances that L. Uttorea has a black head and a heavy shell 

 of brown or olive color. L. rudis ' is 

 smaller, its shell has an angle at the apex 

 of 60° to 70°, and varies in color from white 

 to red. L. palliata - has a shell with an 

 apical angle of 95°, and varying from white 

 to orange, slate, or brown. 



Nat'ica is another common species 



■ ,i ,. , J- J- 1, V, II Fig. 20.5. — A'afica (Luna- 



With an entire aperture to the shell. ^-^^ ,,^„„^^., Two-thirds 



It can be at once distineuished from nat. size. Photo, by 



W. H. C. P. 

 Littorina by the " umbilicus," or de- 

 pression situated at the left of the mouth and in the axis of 

 the shell (Fig. 205). In the living animal the shell is often 

 quite enveloped by the large fleshy foot. The members of 

 this genus lay their eggs in spiral " collars " made of ag- 

 glutinated sand. These are common objects of the seashore. 

 Ful'gur ' is a good example of a prosobranch having a canal 

 at the mouth of the shell. The canal exists for the purpose of 

 containing the siphon by which water is brought to the animal 

 as it lies buried in the sand. Fulgur is our largest common 

 gasteropod. 



Its shell is about 150 millimetres long, and pear-shaped. In 

 one species the margins of whorls are grooved (Fig. 206) ; in the 



'Rough, rude. ^ A cloak. 'Lightning. 



