i9° Bulletin 29 354 



of shell 24, altitude 23, diameter 12, semidiameter of left valve 5, 

 of right valve 7 mm. This shell has a slight resemblance in 

 sculpture to P. Gabbi but that has only one interstitial thread 

 and is twice as large and less oblique in form. 



Locality. — (Exp'd '16) Trail from Hato Viejo to Potrero, 

 Rio Amina. 



Genus Amusium Bolten 



Amusiwn papyraceum Gabb 



Plate 26, Figure 22 



Pleuronectia papyracea Gabb, Trans. Amer. Phil. Soc, vol. 15, p. 



257, 1873. 

 Amusium papyraceum Dall, Trans. Wagner Inst. Sci., vol.3, pt. 4, 



p. 718, 1898; pt. 6. p. 1586, 1903. 



Shell with one valve concavely flattened, the other slightly 

 convex; resembling the Oriental living species in being entirely 

 smooth externally, except for occasional concentric growth lines. 

 Marked internally with paired radiating ribs. Our most perfect 

 shell measures 60mm. in altitude and approximately 58 in length, 

 but we collected fragments of much larger specimens apparently 

 100 mm. in altitude. The Miocene-Recent A. Mortoni Ravenel 

 is allied and possibly identical. A. papyracea is also found at 

 Bowden, but Santo Domingo is the type locality. The shell has 

 never before been figured. 



Localities. — (Exp'd' 16) Samba Hills at an approximate al- 

 titude of 540 feet near Los Caobas; Zone F, Rio Gurabo at Los 

 Quemados; Guayubin to Mao road, Rio Cana; Zone I, Rio Cana 

 at Caimito. 



Genus Spondylus* Linne 



Spondylus bostrychites Guppy 

 Plate 32, Figure 4 

 Spondylus bifrons Sovverby, Quart. Jour. Geol. Soc, London, vol. 6, p. 



*The references to this and other genera in the description of our route, 

 pp. 3 to 10, were rough field notes made before the collections were studied. 



