TERTIARY MOLLUSCA. 137 



Pecten (JSquipecten) decorus, new species. 

 (Plate 13, Figures 8 a, b.) 



The following is a description of this species : 



Shell small, equivalve, moderately convex, slightly oblique, with about 25 

 ribs, of which one or two are obsolescent; hinge-line three-fifths the entire 

 length of the shell; submargins narrow, with obsolete ribs, merging with the 

 disk; ears large, equal, with 8 or 9 scaly radiating riblets, posterior ears 

 rectangular, byssal notch about one-half the length of the ear; secondary 

 sculpture of scaly riblets, 3 on each rib and 3 in each interspace, scales spaced 

 3 or 4 per millimeter, concave towards the umbones, erect or inclined toward 

 the margin. 



Alt. 30 mm., lat. 29 mm., diameter of united valves 15 mm. 



The type, a specimen with united valves, is unique. 



Locality. Disintegrated limestone in quarry near the asylum near 

 Guajay, 15 miles southwest of Havana, Cuba, Barnum Brown, col- 

 lector. 



Geologic horizon. Oligocene. 



Type. American Museum of Natural History. 



Pecten (JEquipecten) oxygonum Sowerby? 

 (Plate 8, Figure 5.) 



Pecten oxygonum Sowerby., Quart. Journ. Geol. Soc. London, vol. 6, p. 52, 1849. 

 Pecten exasperatus Guppy, Quart. Journ. Geol. Soc. London, vol. 22, p. 294, 1866. 

 Pecten angusticostatus Gabb, Trans. Amer. Phil. Soc., new ser., vol. 15, p. 256, 1873. 

 Pecten (dZquipecteri) oxygonum Dall, Trans. Wagner Inst., vol. 3, p. 713, 1898. 

 Pecten (JZquipecten) oxygonum Brown, Proc. Acad. Nat. Sci. Phila., p. 601, 1913. 



The following is the original description of this species : 



"Testa suborbicularis, subobliqua, tumida, costellis radiantibus 19, superne 

 acutangulis, mterstitiisque aequalibus lineis incrementi concinne decussatis; 

 auribus inaequalibus, laevibus, radiatim costellatis, costellis tenuissimis." 



The following is a new description of this species : 



Shell suborbicular, slightly convex, with 19 or more low, rounded, radiating 

 ribs, separated by equal, shallow interspaces; secondary sculpture of numerous 

 narrow, radiating threads. Length, 35 mm. 



We possess of this species only two fragments which it would be 

 unsafe to identify without material for comparison ; there can be little 

 doubt, however, that they represent the species reported by A. P. 

 Brown from the same locality and identified by him from specimens 

 from Santo Domingo, where the type of Pecten oxygonum was collected. 



Locality. Lower bed at Hodge's Bluff, Antigua, station 6862, 

 Vaughan; Santo Domingo, Bowden. 



Geologic horizon. Oligocene. 



Type. British Museum? 



Figured specimen. U. S. Nat. Mus. No. 167065. 



