ACMAEIDAE 105 



Terebra, Oliva, Olivella, Nassarius, and Cerithiu^n leave characteristic 

 footprints and generally may be turned out from the sand at the 

 trail's end. 



Along the southwest Florida coast and on the outlymg islands 

 are many midden sites of the aboriginal key-dwellers, and in these 

 mounds are found numerous implements made from the shells of 

 Fasciolaria and Busycon. These shell tools have holes for handles, 

 and some of them show marks of the thongs which bound these 

 handles in position. Smaller shell tools may have been used to break 

 the shells of living conchs which were used for food. The middens 

 are mainly of oyster shells. 



Order ARCHAEOGASTEKOPODAi^s 



Family ACMAEIDAE 



Atlantic species of the genus AcTnaea occur from far north to 

 Florida and the West Indies. In general, they are mollusks of the 

 littoral region, living among sea grasses and weeds or upon rocks; 

 few deep water species are known. The animal has eyes placed at 

 the upper part of the base of its long, cylindrical tentacles and has a 

 proboscis bordered with fringelike processes. 



The shells are conical, oval, and open at base, more or less de- 

 pressed; apex not perforate, inclined forward, nearest to the anterior 

 border of the shell. The interior is concave — saucerhke. 



Genus ACMAEA Eschscholtz, 1830 

 Acmaea antillarumi^s (Sowerby) 



Alt., 6; length, 20; width, 11 mm. Summit well elevated, not 

 acute; surface with numerous diverging rays of blue-gray on a 

 lighter background. Interior blue-white with alternating dark and 

 light markings about the margin and with a horseshoe muscular 

 impression open toward the front. 



Family FISSURELLIDAE 



This is a widely distributed family of mollusks, all of which 



1'^^ Gr., archaios, ancient; ancient gasteropods. 

 i''^ Gr., acme, point, prime; of the Antilles. 



