326 Americaji Seashells 



2 to 3 inches in length, similar to tuberculatus. Girdle scales glassy. 

 End valves with rather even, raised, radiating threads. Middle valves with 

 the lateral areas bearing about 8 raised threads which split in two at the margin 

 of the valve. Central area with about 6o to 70 even, longitudinal threads. 

 Posterior valve with 19 to 20 prominent slits. Common. The closely re- 

 sembling species, C. stokesi Broderip, from Mexico to West Colombia has 

 only 15 to 16 slits in the posterior valve. 



Subfamily ACANTHOPLEURINAE 



Genus Acanthopleura Guilding 1829 



Subgenus M auger ia Gray 1857 



Acanthopleura granulata Gmelin Fuzzy Chiton 



South half of Florida and the West Indies. 



2 to 3 inches in length, usually so worn and eroded as to eliminate the 

 brown color and granulated sculpturing. Girdle thick, ashy white with 

 an occasional black band, and matted with coarse, hair-like spines. Underside 

 of valves colored a light-green, with the middle valves having a rather large, 

 black splotch behind the sinus. Posterior valve with about 9 slits. Compare 

 with Ceratozojja rugosa whose gills do not extend to the very posterior end 

 as they do in this species. Common. 



Genus Tonicta Gray 1847 



Resembling Chiton in having pectinate or toothed sutural plates, but 

 the girdle is naked and the upper surface of the valves have microscopic 

 eyes. 



Tonicia schrammi Shuttleworth Schramm's Chiton 



Figure 676 



Southeast Florida and the West Indies. 



About an inch in length, colored a brownish red to buff and with 

 darker mottlings and speckles. Upper surface of valves glossy; interiors 

 white with a crimson stain in the center. Lateral areas separated from the 

 smooth central area by a strong, rounded rib. The central area has a pep- 

 pering of about 75 tiny, black eyes. Head valve smooth except for 8 to 10 

 broad rays of tiny, black eyes. Girdle naked, leathery and brownish to flesh- 

 colored. Posterior valve with 14 slits. 36 lamellae in each of the 2 gills. They 

 begin just behind the juncture of the head and the foot and extend back 

 almost to the posterior end where there is a bilobed, small, fleshy lappet. 

 A moderately common, intertidal species. 



