88 PROCEEDINGS OF THE NATIONAL MUSEUM vol.70 



ALABINA CERITHIDIOIDES Dall 



Alaba? cerithidioides Dall, Bull. Mus. Comp. Zool., vol. 18, p. 258, 1889. 



Bittium (Styliferina) cerithidioide Dall, Trans. Wagner Inst., vol. 3, p. 276, 

 pi. 16, fig. 8, 1892. 



Bittium (Elachista) cerithidioide Dall, Porto Rico Rept., p. 427, 1901; Nau- 

 tilus, vol. 15, p. 58, 1901. 



Alabina cerithidioides Dall, Nautilus, vol. 15, No. 11, p. 127, 1902. 



Off Georgia, two specimens. Station 2315, off Key West, Fla.,in 

 87 fathoms, coral, United States Fish Commission. Widely spread 

 in the Antilles in moderate depths of water. Mayaguez Harbor, Porto 

 Rico, 25-30 fathoms. 



The specimens are probably washed from lesser depths of water. 



Family MATHILDIIDAE 



Genus MATHILDA Semper 



MATHILDA GEORGIANA, new species 



Shell small, translucent white, with an inverted smooth nucleus 

 and seven and a half subsequent whorls; suture distinct, not deep; 

 axial sculpture of numerous rounded threads crossing from suture to 

 suture, nodulous at their intersections with the major spirals, and with 

 much wider interspaces; the incremental lines are not conspicuous; 

 spiral sculpture on the spire of two, and on the last whorl of thi'ee, 

 major cords, the former near the periphery with a wide interval be- 

 tween them; there are also fine threads, two behind the posterior cord, 

 on the last whorl one between the peripheral cords and about eight on 

 the flattish imperforate base which is not crossed by the axials except 

 incremental lines; aperture rounded, margin thin, the inner margin 

 with no chink behind it. Length of shell, 9.5; of aperture, 2.5; diam- 

 eter, 4.2 mm. U. S. Nat. Mus. Cat. No. 108353. 



Off Georgia, in large numbers. 



This is one of the commonest forms found at this locality. 



An examination of the radula of M. diomedae Dall, from Hawaii, 

 shows a close relation of this genus to the Turritellidae. 



MATHILDA YUCATECANA Dall 



Mathilda yucatecana Dall, Bull. Mus. Comp. Zool., vol. 18, p. 266, pi. 20, 

 fig. 7, 1889. 



Shell small, pale brownish fading to white, w.ith an inverted smooth 

 nucleus and nearly six subsequent whorls; suture appressed; whorls 

 well rounded, strongly sculptured; axial sculpture of numerous equal 

 thi-eads with wider interspaces, the threads most visible in the inter- 

 spaces of the spirals; the sutural region is somewhat constricted; spiral 

 sculpture of (on the spire two, on the last whorl three) strong cords 

 near the periphery, with wider interspaces, more or less angulating 



