The Top Shells and Dolphin Shells 



The Snake-skin Top Shell (C. pellis-serpentis. Wood) is 

 well named. The heavy, solid shell is i J to 2 inches in diameter, 

 a little higher than broad. Its crowded coils are separated by 

 linear sutures, and finely marked with dark patches in intricate 

 patterns on yellow or pink ground colour. The aperture is lined 

 with pearl; the columella bears a heavy tubercle in the middle, 

 and a small tooth where it joins the thin lip of the aperture. 



Habitat. — Gulf of California to Panama. 



Genus NORRISIA, Bayle 



Shell large, round, umbilicated, solid, smooth; spire depressed, 

 conical; whorls few, rapidly enlarging; aperture quadrangular; 

 outer lip sinuous, thin edged; columella sinuous. An isolated 

 genus of one species. 



Norris's Top Shell (N. TVom'izV, Sby.) is a common species, 

 living upon the giant kelp on rocky beaches southward from San 

 Francisco. The dome is depressed and tipped over by the 

 enlarged body whorl. The apex is blunt; the sculpture consists 

 of faint radiating lines. The colour is a rich brown turning black 

 at the mouth of the wide umbilicus which has a greenish lining 

 rim. The lip is thin-edged. The aperture is large and lined 

 with pearl. A shaggy coat roughens the outside of the operculum ; 

 inside it is smooth and multi-spiral, with a central nucleus. 



This species is abundant about San Diego, where it is often 

 seen in tide pools, with the strawberry-red body extended, crawl- 

 ing on seaweed. Shells are picked up on the beaches after violent 

 storms. It measures one to two inches in altitude, and about two 

 inches in diameter. 



Habitat. — Southern California. 



Genus CALLIOSTOMA, Swains. 



Shell pyramidal, with beautiful colouring and sculpturing; 

 base flattened. A large genus of unusually beautiful shells. 



The Ringed Top' Shell (C. annulatum,M3irtyn) is a specimen 

 people are always interested in collecting. It is abundant in 

 many places along our Pacific coast. Its shell is fragile, and can 

 only be collected in fine weather, and then by going out in a boat 

 and gathering the seaweed to which these delicate creatures cling. 



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