14 THE NAUTILUS. 



ser., ix 234, pi. 34, fig. 5, 1845). Dr. Ball (Trans. Wagner Free Inst. 

 Sci., iii, pt. iv, p. 813, 1898) suggests that this may possibly be the 

 same as Teredo calamus by the same author (op. cit., fig. 4) which 

 apparently differs only in size. The position of T. fistula has always 

 been questioned owing to the absence of all shell characters. Among 

 the above-mentioned material is a specimen having a total length of 

 58 mm. with valves about 12 mm. in length imbedded in the lower 

 end of the tube as shown in fig. 1. From this it will be seen that it 

 evidently belongs to the genus Teredina, although I have seen no 

 trace of the tube being separate, and the number of accessory valves 

 are poorly defined, the small, dorsal, triangular space having but a 

 slight median and transverse groove. The valves are divided into 

 three areas by two faint radial lines which interrupt the concentric 

 lines as shown in fig. 2. On the anterior angle near the margin are 

 traces of a fine squamose imbrication over-riding the concentric lines. 



A NEW SPECIES OF PLEUROTOMA FROM THE PLIOCENE OF CALIFORNIA, 



BY WILLIAM JAMES RAYMOND. 



Subgenus Genota H. and A. Adams, section Dolichotoma Bellardi. 

 Genota riversiana, new species. 



Shell narrowly fusiform, spire elevated, outline of spire contained 

 within two straight lines; whorls slopingly shouldered, convex 

 anteriorly, slightly concave near the suture, an obtuse angle separat- 

 ing the wider convex area from the narrower concave area, whose 

 widths are in the ratio of five to four ; posterior margin of the whorls 

 strongly appressed, suture distinct ; first two or three whorls broken 

 away, later whorls with conspicuous, elevated, revolving threads, of 

 which about eight below the shoulder and six above are more 

 prominent, those above somewhat finer and closer ; between the pri- 

 mary threads are much finer, secondary threads ; on the last whorl 

 about sixteen principal threads below the shoulder, coarser and more 

 widely spaced anteriorly, with one to three secondary threads 

 occupying each interspace ; axial sculpture consisting of sharp, ele- 

 vated growth lines, elegantly decussating the revolving threads, 



