4 PROCEEDINGS OF THE NATIONAL MUSEUM vol.79 



which passes abruptly into the postnuclear sculpture without inter- 

 mediate stages. The postnuclear whorls are marked by slightly pro- 

 tractively slanting, rather broad axial ribs, which are strongest on 

 the early turns and which become enfeebled on the later and are 

 quite obsolete on the last whorl. Of these ribs 11 occur upon the 

 first postnuclear turn, 12 upon the second, 14 upon the third, 18 upon 

 the fourth, while upon the next they are quite poorly expressed and 

 irregular. In addition to the strong axial ribs, the entire surface 

 of the whorls on spire and base is marked by numerous fine axial 

 threads. The spiral sculpture also presents considerable variation. 

 On the first whorl there are two strong spiral cords, one on the 

 middle of the whorl, the other near the periphery. These cords are 

 almost keels and render their junction with the axial ribs decidedly 

 tuberculated. On the second turn two slender spiral threads appear 

 between the summit and the first cord, and a third is present between 

 the two strong cords. These threads become much more strongly 

 developed upon the next whorl. On the fourth turn the strong keels 

 are decidedly reduced almost equal to the rest of the spiral cords, of 

 which 12 are here present between summit and suture. These are 

 not all of the same strength, the intercalated threads being a little 

 weaker than the rest. The fifth whorl shows 15 spiral threads, while 

 on the last 23 are present between the summit and the periphery. 

 Here they are subequal and subequally spaced, the spaces separating 

 them being about equal to the spiral threads. Suture moderately 

 constricted. Periphery well rounded. Base gently rounded, marked 

 by 25 spiral threads, which are alternately strong and feeble. Colu- 

 mella moderately short, marked by 14 very oblique spiral threads. 

 Aperture elongate-ovate, decidedly channeled anteriorly with a mod- 

 erately broad and moderately deep sinus immediately below the 

 summit on the outer lip ; outer lip evenly curved, moderately thin at 

 the edge, which is rendered finely denticulate by the spiral threads 

 on the outside; inner lip and parietal wall marked by a slightly 

 impressed smooth area, resembling a callus. 



Type.—U.S.'NM. No. 368134, collected by C. D. AUeman on Taboga 

 Island, Panama. It measures: Length, 12.8 mm.; diameter, 4.5 mm. 



Remarks. — Daphnella clathrata Gabb appears to belong here, also 

 an undescribed species from the Gulf of California. 



MITRA (SCABRICOLA) MARSHALLI, new species 



Plate 1, Figure 4 



The shell is rather small, elongate-ovate, and dark chestnut- 

 brown. The early whorls badly eroded in the type. Those remain- 

 ing subtabulatedly shouldered at the summit; the rest only very 

 slightly curved. The whorls are marked by rather strong, almost 



