NO. 1569. WEST AMERICAN MOLLUSKS—BAETSCH. 259 



The basal portion of the outer hp is closely appressed to the coliimellar 

 callus and completely closes the anterior channel, leaving only a 

 round perforation at the anterior extremity of the columella. 



The specimen described and figured, Cat. No. 195376, U.S.N.M., 

 has fifteen v.diorls and measures: Length, 4.1 mm.; diameter, 1.1 mm. 

 It was dredged by the steamer of the U. S. Bureau of Fisheries steamer 

 Albatross at Station 2798, in 18 fathoms, in the Bay of Panama. The 

 type lot, No. 208 C. B. Adams collection, at Amherst, New Hamp- 

 shire, contains ten specimens, none of wliich are as well preserved as 

 the one figured. 



A color form of tliis species has the posterior and mechan keel wliite, 

 wliile the supra-peripheral one and the base are light brown. I will 

 suggest for this form the varietal name, hicolor, fig. 6, Cat. No. 195376, 

 U.S.N.M., dredged hj the Fisheries steamer Alhatross at the same sta- 

 tion. Another specimen of this form was found among C. B. Adams 

 type lot of Triphoris alfernatus from Panama. 



TRIPHORIS ALTERNATUS C. B. Adams. 



Piatt" XVI. tig. 11. 



Triphoris alhrnatus C. B. Adams, Ann. Lye. Nat. Hist. N. Y., V, 1852, pp. 382-3. 



Shell regularly elongate-conic, with the median and anterior spiral 

 row of tul)ercles wax yellow, and the rest of the spire, periphery, and 

 base brown on the later whorls. Nuclear whorls live, wax yellow, 

 ornamented by two spiral ridges, the posterior one of which falls on 

 the middle of the turns and the anterior about half way between 

 this and the anterior suture. In addition to this they are crossed by 

 many slender raised axial threads, thirty-two of which occur upon the 

 last turn. The whorls are sloping!}^ shouldered from the posterior 

 keel to the summit. Post-nuclear whorls separated by deeply chan- 

 neled sutures ornamented on the early turns by two strongly tuber- 

 culiite s])iral keels — one at the summit, the other at the periphery. 

 The tubercles are formed by the intersection of the spiral keels and 

 the axial ribs and slope rather suddenly posteriorly and roundly 

 toward their anterior limit. Begimiing with the fifth post-nuclear 

 whorl a slender spiral cord makes its appearance in the middle of 

 the broad channel between the two keels; this increases steadily in 

 size, and on the last turn bears tubercles which ecpial those of the 

 anterior keel in strength. Axial ribs somewhat retractive, eighteen on 

 the first, twenty upon the fifth, and twenty-two upon the penidtimate 

 whorl. The spaces inclosed between the spiral keels and axial ribs are 

 deep oblong pits, the long axis of which coincides with the spiral keels. 

 Periphery of the last turn marked by a strong spiral keel. Base 

 well rounded, marked by two strong spiral keels, the posterior one of 

 which agrees with those posterior to it in spacing and is weakly 

 tuberculated, while the anterior one, which is situated on the base 



