242 PATAGONIAN EXPEDITIONS I PAL/EONTOLOGY. 



Record of specimens: Mouth of Santa Cruz River, 3 sp. 



Affinities: Within the genus Drillia we know a few species in which a 

 collosity of the inner lip is combined with the character of slight develop- 

 ment of spiral sculpture, but in most of them spiral lines are present at 

 least in the lowermost part of the shell (on the canal). A complete lack 

 of this sculpture is given for D. perpolita Ball (1890, p. 36, pi. 2, f. 2), 

 Pliocene and Recent, West Indies and southern United States, but the 

 latter has no callosity. Species, which have a callosity, but have traces 

 of spiral ribs, are, for instance, D. kceneni Speyer (1867, p. 203, pi. 22, f. 

 6, 7), Oligocene, Germany, D. sigmoidea Bronn, Pliocene, Europe. The 

 most closely allied species seems to be D. limatula Conrad. In the 

 Princeton Museum there are 7 specimens of this species from the Miocene 

 of St. Mary's River, Maryland, which agree in the complete lack of spiral 

 sculpture and the presence of a callosity, as well as in the presence of a 

 sutural depression with our Patagonian fossil. The differences, however, 

 are: (i) the number of longitudinal ribs is less (9-11); (2) the sutural 

 depression is less distinct, the ribs not ending so abruptly ; (3) the shape 

 of the shell is less elongate. 



Gen. BORSONIA Bellardi. 

 169. BORSONIA PATAGONICA Ortmann. 



PI. XXXVII, Fig. 4-*. 

 1900 B. p. Ortmann, in Amer. Journ. Sci., v. 10, p. 377. 



Shell subfusiform, biconical ; whorls, about 6 ; last whorl a little larger 

 than half of the shell, Whorls convex, depressed in the upper part, with 

 a slight swelling just below the suture ; depressed part smooth (except 

 for lines of growth), the rest ornamented by 10-12 longitudinal, rib-like 

 swellings, which are slightly tuberculiform on the upper whorls; on the 

 last whorls they are rib-like, but less distinct, and tend to disappear 

 toward the mouth. Besides the ribs, there are spiral cords on the lower 

 part of the whorls, which are wanting on the depressed part, but continue 

 on the last whorl upon the canal. Mouth elongate, canal of medium 

 length. Outer lip with a moderately developed sinus, which is situated 

 in the sutural depression. Columella with two plaits, of which the lower 

 one is sometimes quite indistinct. 



