361 



less promiQent rib like folds. As its mouth characters are almost entirely 

 unknown, it is by no means certain that it belongs to the genus Mesos- 

 toma. 



Mesostoma (?) Xewcombii. (N. Sp.) 



Plate 43, fig. 5. 



Shell elongated, slender, more than twice as long as wide : volutions 

 nine or ten, sliglitly and rather obliquely compressed above or poste- 

 riorly, most prominent and rounded below their midheight anterior- 

 ly ; outer volution short, apparently rounded at its base ; characters of 

 the aperture unknown, though the outline of a transverse section of the 

 interior of the last volution near the aperture is obliquely oval. 



Surface marked with rather large, low, distant, rounded rib-like folds, 

 that cross the lower part of each volution transversely and are obsolete 

 above, also by numerous, very small and close set spiral ridges. 



Approximate dimensions of the only specimen known to the writer, 

 which is slightly imperfect at both ends : length, sixty-six millimetres ; 

 greatest breadth, twenty-live mm. 



Sucia Islands, Dr. C. F. Newcombe, 1896 : one specimen. 



Apparently a much larger species than the preceding, with volu- 

 tions of a different shape, and with different surface markings. It is, 

 however, quite doubtful to what genus this shell .shQuld be referred, and 

 It is only provisionally regarded as a Mesostoma. 



Cerithium Vaxcouverense. (N. Sp.) 



Plate 4.1, fig. 6. 



Shell small, elongated, slender, apex apparently acute, volutions pro- 

 bably about eight or nine, though onl}- six are actually preserved in the 

 best specimen that the writer has seen, and compressed laterally ; spire 

 rather more than twice as long as the outer volution, which is also com- 

 pressed at the sides, and narrowly rounded at the base or anteriorly ; 

 characters of the aperture unknown. 



Surface marked by strongly defined, straight ribs, that cross the volu- 

 tions of the spire and upper half of the outer volution transversely, and 

 by spiral rows of small, spirally elongated tubercles. As viewed dorsally, 

 there are four rows of these tubercles on the later volutions of the spire, 

 and on the outer volution there are three or four rows of tubercles above 

 the midheight, and six or seven small spiral ridges without tubercles 

 below. 



