The Cross-barred Shells 



owners to Dr. Dall at the United States National Museum in 

 Washington, D. C. He has given names to them. The speci- 

 mens thus for the first time christened by a scientist are the 

 "types" of the new species. Specimens found later are com- 

 pared with the type to determine what they are. "Types" are 

 usually preserved in great museums. 



C. cancellata, Linn., has a thick shell studded all over with 

 sharp points left by the intersection of deep furrows crossing each 

 other. Two bands of brown decorate the body whorl, one cir- 

 cles each whorl above. The ground colour is creamy white. 

 The throat of the shell also has sharp ridges and teeth. 



This ornamental shell is hidden in life by sand. The foot, 

 unprotected by an operculum, has a sandy coat on the bottom, 

 so that when it is pulled in the aperture seems to be plugged with 

 sand. The species is found on sandy bottoms at four or five 

 fathoms depth. The sand is no doubt a protection. The creature 

 is slow and timid. It can extend the head and foot to surprising 

 lengths. Length, I -to I J inches. 



Habitat. — -West Africa, Mediterranean Sea. 



C. Stimpsonii Calkins, is a colourless tropical species. 

 Its whorls are angulated and noduled, the surface below the 

 shoulder decorated with rows of smaller projections. There are 

 two plaits on the columella. The oval aperture ends in a short 

 canal. Length, | inch. 



Habitat. — Cape Sable, Florida. 



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