3 2 Bulletin 29 196 



Terebra (Oxymeris) gatunensis Toula, Jahrbuch der K— K. Geol. 

 Reichsanstalt Wien, vol. 58, p. 705, pi. 25, fig. 14, 1908. 



Terebra gatunensis Brown and Pilsbry. Proc. Acad. Sci. Phila., pp. 



339- 34o, pi. 22, fig. 2, 191 1. 

 Terebra (Myurelta) gatunensis Cossmann, Jour, de Conchyliologie, 



vol. 61, pp. 13, 14, pi. 1, figs. 26-29, I 9 I 3- 



Shell slender, tapering to a very acute spire, whorls of a 

 decollate specimen 13, each whorl ornamented with a subsutural 

 band about a quarter the width of the whorl. The band is 

 marked off by a sulcus beneath which are typically seven, more 

 often six, spiral cords. (The seventh frequently being concealed 

 by the following volution). Transverse sculpture of many, very 

 fine riblets which traverse the subsutural bands in a nearly ver- 

 tical direction, but swing back slightly at the furrow, then be- 

 come somewhat arcuate on crossing the seven spirals. Toula 

 mentions twelve riblets on half a volution. This is the case 

 with a diameter of 8.5 mm., that of Toula's specimen, which was 

 a young shell; but the number of riblets increases on the later, 

 larger whorls. Columella hardly plicate, but sharply keeled at 

 the back. 



Length of decollate shell 50 mm., greatest diameter 10.5 

 mm. 



This species can easily be distinguised from T. spirifera and 

 T. cirrus (of the T. bipartita group), which it resembles in sculp- 

 ture, by their both possessing two sharp plications on the colum- 

 ella, while gatunensis is nearly smooth, with only a faint sug- 

 gestion of a single fold. It is more difficult to discriminate be- 

 T. gatunensis and some variations of T. Wolfgangi, as these two 

 species are very closely allied. 



T. gatunejzsis is found on the Isthmus at Gatun, Mindi, and 

 Monkey Hill ; and Cossmann refers a fragmentary shell from Mar- 

 tinique to this species. 



Locality. — (Exp'd '16) Bluff 3, Cercado de Mao. 



