166 PROCEEDINGS OF THE ACADEMY OF [April, 



Mitra tortuosella frater n. subsp. 



This form is closely related to the preceding, but differs by having 

 deeply cut spiral grooves about as wide as the raised cords, in the 

 intercostal intervals. There are 7 or 8 grooves on the penult whorl 

 which has 15 slightly arched axial ribs. The anterior canal is shorter 

 than in M. tortuosella. 



Length 14.7, diam. 5 mm.; 8 whorls, the apical ones lost. Further 

 series are needed to determine the value of the differences between 

 this form and the preceding. 



Type No. 3286. 



Mitra mesolia n. sp. 



The shell is short and stout. Sculpture of a few impressed spiral 

 lines on the upper part of the last whorl and the spire, 6 on the 

 penult whorl, the anterior end having about 9 low spiral ridges, with 

 faint traces of spirals above them, the middle part of the last whorl 

 being smooth. Lip thickened within in the lower three-fourths, 

 smooth; 4 columellar plaits. 



Length 20 (apical whorls wanting), diam., 9.5 mm. 



This species is shorter than the Galifornian M. maura which it 

 resembles. In a younger specimen only a small part of the last 

 whorl is unsculptured. 



Type No. 3275. 



Plochelaea gabbi n. sp. 



The shell is smaller than P. crassilahrum. Spire concavely conic, 

 of 7| flat whorls. First 2 whorls form a nipple-like apex; the next 

 2 or 3 are very delicately striate spirally; subsequent whorls showing 

 faint groAvth-lines only. Suture not impressed, suddenly ascending 

 to or very nearly to the summit of the last whorl, in front. Last 

 whorl has more convex outlines than P. crassilahrum, and terminates 

 in a very low, wide varix. The outer lip is subacute in the upper 

 part, but a little blunt and slightly reflected in the lower half. It 

 is not inflected. The upper third of the aperture is narrow, lower 

 two-thirds dilated, widest just above the basal channel, which is 

 deep and recurved. There are 4 narrow, nearly horizontal columellar 

 plaits, and al)ove them 3 distinct and one or tw^o vestigeal, smaller, 

 slightly ascending plaits in one specimen, but in the type only two 

 short plaits above the four strong ones. 



Length 25 , diam. 12.7, length aperture 22.3 mm. 



'' 27.4, " 12.7, '' " 24.2 " (type). 



The shorter spire, stronglj^ ascending anterior end of the suture, 

 and the straightened but not inflected outer lip, amply distinguish 



