17 American East Coast Arcas 17 



nomenclature of this species which I have not the literature to straighten out. As far 

 as I am now able to ascertain, tlie first name applied to this shell was Candida, and the 

 first binomial Latin name was that of Gmelin. It is a well known West Indian species 

 conspicuous for its large size, white shell, and compressed, flattish valves. It is quite 

 possible that some of the early authors named this wide-spread species more than once, 

 and in this connection the A. ovata and complanata should be examined." 



Recent and fossil shells from the Caribbean district reported as A. velata Sowerby 

 are probably this species. 



"Shell thin to solid, rather compressed, subtrapezoidal, gaping at the anterior base; 

 anterior end generally truncate; posterior end pointed and obliquely truncate above; 

 beaks high, separated by a moderately wide area; surface sculptured with fine to rather 

 strong double or single, large or small ribs which are heavier on the posterior slope. 

 These are crossed by rude, irregular growth lines and ridges, causing the surface to ap- 

 pear somewhat cancellated and beaded; epidermis heavy, shaggj'; teeth feebly devel- 

 oped. Color v.'hite. 



"Length, 60; height, 35; diameter, 28 mm," — Dall and Simpson, (Mollusca of 

 Porto Rico, Bull. U. S. Fish Comm., vol. 20, for 1900, pt. i, p. 460, 1901). 



Ocmrroice. — Oligocene of the Bowden beds, Jamaica, of the Chipola beds at Alum 

 Bluff and on the Chipola River, Florida: Pliocene of Trinidad; Pleistocene of the An- 

 tilles generally, and recent from Cape Hatteras, North Carolina, to Brazil at Santa Cat- 

 erina, and possibly the African coast. — Dall. Recent from Santo Domingo. — C. U. 

 Museum. 



Area caloosahatchiensis (new name) 

 Plate III, Figure 13 



Barbatia {Calloarca) irregularis Dall, Wagner Free Inst. Sci., Trans., vol. 3, pt 4, p. 623, pi. 33, 



fig. 5. 1S98. 

 Not Area irregularis Deshayes, Des. Coq. Fos., vol. i, p. 208, pi. 32, figs. 9, 10, 1830. 

 Not Area irregularis d'Orbigny, Pal. Franf., Terr. Cret., vol. 3, p. 240, pi. 326, figs. 4, 5, 1844. 



"Shell thin, elongate, irregularly distorted; beaks prosogyrate; at the anterior 

 third rather low and compressed; cardinal area long, rather narrow, with very numerous 

 (twelve) concentric grooves; surface irregular, sculptured with nimierous fine radiating, 

 somewhat imbricated ribs, of which those in front of the beaks and on the posterior dor- 

 sal slope tend to be larger and more elevated ; there is a tendency to alternate or pair 

 among the ribs in some specimens; the imbrications or nodules on the ribs are somewhat 

 regularly spaced and correspond to elevated concentric lines in harmony with the lines of 

 growth; the posterior dorsal slope is bounded by rounded ridges radiating from the 

 beaks; the posterior cardinal margin is elevated and angular with more or less of a de- 

 pression between it and the radial ridge on each side; the byssal foramen is wide and ir- 

 regular; the hinge-hne is long and straight; the teeth, vertical and very small medially, 

 are sometimes obsolete in the middle of the hinge; distally they become rather distant 

 and quite oblique, as well as larger; the internal margin, though irregular, is not fluted. 

 Lon. of adult 51, alt. 25, diameter 20 mm. 



