ART. 1. TERTIARY MOLLUSKS FROM THE •>;"]£ST INDIES WOODRING. 5 



The specimen of O. gabU figured by DalP^ (U.S.N.M. Cat. No. 

 112218) is the only known specimen of the genus that shows all the 

 features of the aperture of a shell after the spire is covered. The 

 backward curving of the slender base of the columella gives Orthau- 

 lax a characteristic stromboid appearance. The sinus near the base 

 of the outer lip, a characteristic feature of Stromhus and other 

 genera of the family, is very shallow in Orthaulax. Most of the 

 specimens of O. gdbhi and 0. 'pugnax have three thickened subsutural 

 columellar calluses on the later whorls, and as they are not absorbed, 

 they produce the triangular cross section of these species when con- 

 cealed by growth. On a few specimens of 0. gabhi the callus is thin, 

 producing a subcircular cross section. The type of 0. inornatus 

 has a concealed thickened callus about 40° in a clockwise direction 

 from the callus at the aperture, producing a dorso- ventral compres- 

 sion, but most of the specimens of this species apparently have a 

 thin callus, or the callus is absorbed, as their cross section is circular. 

 As specimens of 0. aguadillensis of different growth stages have a 

 thick subsutural callus at the aperture, it is inferred that the callus 

 is absorbed in this species, which has a circular cross section. The 

 columellar callus of O. caepa and O. cojioides, both of wliich have a 

 circular outline, is not known. 



ORTHAULAX AGUADILLENSIS Maury. 



Plate 1 ; Plate 2, figs. 3-G. 



Orthaulax pugnax Cooke (part), 1919, Carnegie Inst. Wasliington Pnl7. 



291, p. 115, pi. 2, fig. 3. 

 Orthaulax aguadillensis Maury, 1920, Scientific survey of Porto Rico and 



the Virgin Islands, vol. 3, pt. 1, p. 58, pi. 9, fig. 4, New York Acad. Sci. 

 Orthaulax portoricoensis Hubbaed, 1921, Scientific survey of Porto Rico 



and the Virgin Islands, vol. 3, pt. 2, p. 146, pi. 25, figs. 1-5, New York 



Acad. Sci. 

 Orthaulax aguadillensis Maury, Cooke, 1921, U. S. Geol. Survey Prof. 



Paper 129-B, p. 30, pi. 4, figs. 2-6; pi. 5, figs, la, lb. 



The following is the original description: 



Shell large and heavy, form of spire short and blunt, like that of Orthaulax 

 pugnax. This at once distinguishes the shell from the Dominican species. 

 O. inornatus Gabb, which is high-spired. A further characteristic of the shell 

 is the evenly rounded form of the shoulder, which in cross section would be 

 almost perfectly circular. This marks it off very decisively from the Florid- 

 ian, Chipolan species, Orthaulax gabbi Dall, which is markedly triangular at 

 the shoulder. The spire measures 45 mm. in diameter. 



Type locality. — Aguadilla, station 3, Porto Rico. 

 Type. — American IVIuseum of Natural History. 

 The following is a description of specimens from the Republic of 

 Haiti : 



=" Dall, W. H., Wagner Free Inst. Sci. Trans., vol. 3, pi. 12, figs. 5a, 56, 1890. 



