THE NAUTILUS. 7 



base ; growth-lines fine and slight. Light flesh colored. Whorls 

 about 6, the first globose, the second and third with rather coarse 

 longitudinal folds, which persist longer at the upper part of the whorl ; 

 remaining whorls convex, foldless ; the last whorl oval, regularly con 

 vex, contracted below, with a wide arcuately striate siphonal fas- 

 ciole bounded above by a strong narrow spiral rib. Aperture a lit- 

 tle over half the alt. of shell. Columella broadly concave above, 

 having a strongly twisted fold below, which projects at the junction 

 of the short basal canal with the cavity of the aperture, sloping 

 strongly to the left below the projecting fold ; anterior notch wide. 

 Parietal callus rather thin, spreading far forward. 



Length 22'5, diarn. 12 mm. 



Maldonado Bay. This species is certainly not the young of B. 

 cochlidium, although in my opinion d'Orbigny's fig. 25 of plate 61 

 of the Voy. Am. Merid. was drawn from a specimen of the form here 

 described. The characters of columella and sculpture also incline 

 me to consider the present species distinct from B. Lamarckii 

 Kieuer (Iconogr., pi. 3, figs. 6, 6). 



Chlorostoma (Omphalius') corrugatum Koch. Irochus patagoni- 

 cus Orb. is a synonym. 



Columbella avara Say. 



Columbella obesa var. decipiens C. B. Ad. 



Columbella sertulariarum d'Orb. 



Crepidula aculeata Gmel. 



Cylichnella bidentata Orb. 



Fissuridea patagonica d'Orb. 



Halistylus columna Dall. 



Halistyluscircumslriatus n. sp. Similar to H. columna in size and 

 contour, but the whorls are encircled by numerous impressed brown 

 lines. H.pupoideus (Cpr.) Dall, of California, (Proc. U. S. Nat. 

 Mus., xv, 1892, pi. 19, f. 2) is a third species of this interesting 

 group. It is spirally sculptured like circumstriatus, but has very 

 convex whorls, and there are other differences. 



Natlca Isabelleana d'Orb. 



Natica maroccana Dillw. (?). Worn young shells. 



Ocinebra cala n. sp. 



Olivancillaria anricularia Lam. Maldouado Bay ; also fossil 

 specimens in the Fort wall at La Plata Museum. 



Olwella Puelchana d'Orb. 



Scala elegans d'Orb. (probably). 



