NO. 2 rost: the family arcidae 185 



I have examined B. {Cucullaearca) reeveana (Orbigny), the Pacific 

 coast species, and the Atlantic species B. {Cucullaearca) Candida (Hel- 

 bling). Both had only one distinct eye-spot on the anterior part of each 

 mantle margin. A similar arrangement of eyes was found by Pelseneer 

 (1911, PI. 3, fig. 4) in B. {Cucullaearca) nivea (Chemnitz), a species 

 belonging to the same group. As mentioned before, species belonging to 

 Barbatia s. s. seem to have heavily pigmented mantle margins with eye- 

 spots all around. 



Subgenus Cucullaearca, therefore, seems to constitute a supra- 

 specific unit. 



Barbatia (Cucullaearca) reeveana (Orbigny) 1846 

 PI. 11, figs. 4, 5, 9; text-figs. 82 a-c 



Area reeveana Orbigny, Voyage dans I'Amerique Meridionale, vol. 5, 



pt. 3, 1846, pp. 635-636. New name for Area helblingii Bruguiere, 



Reeve 1844 (Conch. Icon., vol. 2. Area, species 90). Not Area 



helblingii Bruguiere 1792. 



Syn.: f Barbatia nova Mabille 1895. 



Fig.: Maury, 1922, PI. 2, figs. 13, 15-17; Reinhart, 1943, PI. 15, figs. 



1-3. 

 Type loc: Santa Elena, Ecuador (designated by Hertlein and Strong, 



1943). 

 Holotype: British Museum ? (Reeve's specimen) 



Remarks: Sheldon and Maury in Maury, 1922, have described two 

 varieties of this species, lasperlensis and velataformis. These varieties are 

 not taken into consideration in this paper, as Barbatia {Cucullaearca) 

 reeveana is variable in form depending upon its environment and so the 

 separation of different forms has no value. The shell is shaped according 

 to the place of its attachment and the space it has at its disposal. Maury 

 (1922, PI. 2, figs. 13, 15, 17) gives figures of specimens with variations 

 in form. The number of posterior ribs is also variable, but seven coarse 

 ribs can usually be counted. The sinus for the byssal gape is usually 

 larger in the right valve. Sometimes, in small and in unworn specimens, 

 one of the valves is complete, with the byssal gape cut in the other valve 

 only. 



The periostracum consists of dark brown spinelike projections, some- 

 times in pairs arranged in concentric rows (PI. 11, fig. 4). The "spines" 

 are connected by a thin brownish-yellow membrane and become very 

 stiff on the posterior part of the shell. 



