Clark: The San Lorenzo Series of Middle California 179 



It is common in the Oligoeene of Oregon and Washington, where it is 

 associated with Cardium lorenzcmum Arnold, Macrocallista pittsburg- 

 cnsis Dall, Leda lincolncnsis Weaver, Agasoma gravidum colum- 

 bianum Anderson and Martin. It is found in the San Ramon 

 formation to the south of Walnut Creek, at University of California 

 locality 1131; here it is associated with a typical Agasoma gravidum 

 fauna. 



FUSINUS (EXILIA) PINOLIANUS, n. sp. 

 Plate 21, figure 2 

 Type specimen 11274, Coll. Invert. Palae. Univ. Calif., loe. 3055 



Shell tall, slender, medium in size ; spire high, acute ; whorls five or six ; body 

 whorl, including canal, a little over half the height of the shell ; whorls rather 

 strongly convex, with sutures deeply depressed. Surface sculptured by about 

 eighteen narrow, rounded, longitudinal ribs, with interspaces not much wider 

 than the ribs; surface also covered by numerous fine spiral ribs, with interspaces 

 usually about twice as wide as the ribs ; on the penultimate whorl there are seven, 

 and on the body whorl about twenty of these spiral ribs. Aperture not exposed. 

 Canal straight ; anterior end broken on all specimens at hand. 



Dimensions. — Height, about 13 mm.; height of spire, 5 mm.; width of body 

 whorl, about 4.5 mm. 



PERSE, new genusi*9 



Shell fusiform, with a medium high spire ; sutures appressed ; upper part of 

 each whorl depressed into a fairly broad collar, which is most distinct on the 

 body whorl. Canal medium in length, straight to slightly curved, narrow anter- 

 iorly ; surface sculptured by spiral ribs and usually with well-developed longi- 

 tudinal ribs or nodes. 



There are several species which appear to fall within the genus 

 described above. The type of the genus, Perse corrugatum, is de- 

 scribed below. Hemifusus washingtoniana Weaver, 150 described from 

 the Tejon of Washington and listed by Weaver from the lower Oligo- 

 eene of that region, also belongs to this genus. There is still another 

 species in the Oligoeene of Oregon which has not been described that 

 belongs to this genus. 



14 o Credit is due to Harold Hannibal for first discerning that the genus here 

 described is new. His observations were based on the form described by Weaver 

 as Hemifusus washingtoniana. As Hannibal does not intend to describe the 

 genus and as the species described below from the San Lorenzo Group of the 

 Mount Diablo region falls within this genus, it seems best for the writer to 

 describe it. 



150 1'or original description of Hemifusus washingtoniana, see Weaver, C. E., 

 Wash. State Geol. Surv., Bull. 15, pp. 46-47, pi. 2, figs. 11, 12, 1912. 



