WEST AMEEICAN PYRAMIDELLID MOLLUSKS. 53 



TURBONILLA (STRIOTURBONILLA) SERR-E Dall and Bartsch. 

 Plate 4, fist^. 8, 3«. 



Turbonilla {Strioturbonilla) serrsc Dall and Bartsch, Proc. U. S. Nat. Mus., 

 vol. 33, 1907, pi. 44, figs. 8, 8a. 



Shell slender, very elongate-conic, subdiaphanous to milk-white. 

 Nuclear whorls two and one-half, depressed, helicoid, having their 

 axis at right angles to that of its succeeding turns, in the first of which 

 they are about one-fifth immersed. Post-nuclear whorls very high 

 between the sutures, moderately rounded, slightly contracted at the 

 periphery and somewhat shouldered at the summit, rendering the 

 sutures subchannelled. The whorls are marked by subequal and sub- 

 equally spaced, rather broad, rounded, almost vertical axial ribs, 

 which are a little wider than the intercostal spaces, the depressed por- 

 tion of the latter terminating a little above the suture. In the type, 

 which has lost the nucleus and probably the first two post-nuclear 

 turns, there are 16 ribs on the third of the remaining whorls, 20 on the 

 eighth, 22 upon the eleventh, and 34 upon the next, the penultimate 

 turn. On this whorl the axial ribs are less regular and less strongly 

 developed, showing senile degeneration. Periphery of the last wdiorl 

 well rounded. Base short, well rounded, marked by slender con- 

 tinuations of the axial ribs, which extend feebly to the insertion of 

 the columella. Entire surface of spire and base crossed by numerous 

 closely placed spiral striations. Aperture subquadrate, posterior 

 angle obtuse, outer lip tliin, columella rather strong, somewhat 

 oblique, and slightly re volute, without apparent fold in the aperture. 

 The type has thirteen whorls and measures: Length 7.7 mm., diameter 

 1.4 mm. 



The type and seven specimens were collected by Mr. S. S. Berry in 

 12 fathoms off Del Monte, Monterey, California; five of these are in 

 Mr. Berry's collection. Tlie type and one other, form Cat. no. 196198. 

 Cat. no. 196200, U.S.N.M., contains a specimen from 40 fathoms 

 off Pacific Grove, Monterey, California, dredged by Mr. Berry. An- 

 other specimen in Mr. Berry's collection was dredged in shelly sand iit 

 Monterey, CaHfornia, at a depth of 29 fathoms. 



This species is nearest related to StrioturhonUla stylina Carpenter, 

 but can readily be distinguished from it by its less rounded whorls, 

 straighter and much stronger ribs, and by having the ribs continuing 

 over the base, and scarcely an}- space showing between the termination 

 of the intercostal spaces and the suture. 



It is named in Iionor of Father Junipero Serra, the early Spanish 

 missionary to California. 



2565— Bull. 08—09 5 



