430 REV. B. BOOG WATSON ON THE 



whorls, which constricts both the ribs and the interstices. On 

 the last whorl there are 18 or 20 shallow and narrow furrows 

 parted by flat interstices of about three times their width ; these 

 do not extend to the sinus-area, and only very doubtfully to the 

 snout, where there are rather a few irregular and scarcely raised 

 rounded threads : these furrows are not recognizable on the 

 earlier whorls. The whole surface is very delicately fretted with 

 almost microscopic, crisp spiral strise whose course is not quite 

 regular, and which are crimped or disturbed by the lines of 

 growth ; this sculpture is particularly sharp and distinct in the 

 sinus-area. Colour pure marble-white. Spire very regularly 

 conical. Apex : there are about two embryonic whorls, which 

 are small, nearly cylindrical, with scarcely appreciable suture, and 

 end in a blunt, round, laterally flattened-down tip. Whorls 10 

 in all, rather short and broad, scarcely at all convex ; the last is 

 large, being broad and tumid, but not long, with a tumidly conical 

 lop-sided base, ending in a short, broad, flat snout which is ab- 

 ruptly and straight cut off. Suture linear, but well defined by 

 the swelling of the infrasutural row of tubercles. Mouth oval, 

 with an acute angle above, an obtuse angle at the side where the 

 body and pillar join, and a truncation at the point. Outer lip 

 thin, a little patulous, with an equable convex curve throughout : 

 the sinus is very shallow and round, with no shelf above it ; and 

 below it is a very high but little prominent shoulder made by 

 the very slightly advancing lip-edge. Inner lip very narrow, 

 shallowly hollowed into the substance of the shell ; the pillar is 

 straight, conical, and is obliquely cut off in front with a blunt, 

 rounded, scarcely twisted edge. H. 0*66. B. - 29. Penultimate 

 whorl, height 0-12. Mouth, height 0-3, breadth 0-14. 



This is a singularly beautiful species, which approaches P. sacra, 

 Eeeve, but has no semblance of an umbilical chink ; the body is 

 broader, the base more contracted, the spire more regularly conical 

 and not at all convex ; the individual whorls are much shorter, 

 the sinus much shallower ; the colour is pure white, not brown- 

 banded ; and the sculpture is deeper and less superficial. 



31. Plettbotoma (Mangelia) subtilis, n. sp. 



St. 122. Sept. 10, 1873. Lat. 9° 5' S., long. 31° 50' W. Off 

 Pernambuco. 350 fms. Mud. 



Shell. — Very small, conical, sharp-tipped, with a lop-sided base, 

 subscalar, ribbed, and with spiral threads; there is a strong labral 



