- G4 - 



general proportions and sculpturing are constant. The length of 

 the two posterior "'.vings" and the depth of the emargination be- 

 tween then are especially inconstant. Prom the other Areas of 

 the fauna occidentalis may he differentiated hy its elongate form 

 and the eharccter of the radial ribbing. The small A. paratina 

 Dall (1) , of the Florida dhipola sjid Tampa silez "beds, very much 



(1). Dall, ''!, 'f^-,, Trans. ,7agne r Free Inst. 3ci., Philadelphia, 

 vol. 4, pt. 4, pp. 621-62?, nl. 5-'^, fig. 14, 1098. 



resembles A. ocoidentalis in many characters, but v;hen compared with 

 occldentalis of the same size, is usually less alate posteriorly, 

 proportionately longer, with a more ujiiform outline, more delicate 

 and more numerous ribs. 



This s^oecies a')parently is the form \iiich Petiver (2) designat- 

 ed "Mytilus Barbadensis, vulgaris, striatus, striis fuscis" - cited 



(2). Kern. nat. cur., p. P'^-?, no. 62, 1708. 



by Sloane in his "LTatural History of ramaica". (") '■I'his name was 



(5). Voyage to the islands l.Iaderia, 3aroc,does, llir-veR,^ St. Jhris- 

 tophers and Jamaica; vn.th the Eatural Kistory ...... , of the 



last of these Islands, vol. 2, p. 257, no. 9, 1725. 



