REPORT ON THE GASTEROPODA. G03 



29. Rissoa (Ceratia) transenna, 1 n. sp. (PI. XLV. fig. 9). 



Station 145. December 27, 1873. Lat. 46° 43' S., long. 38° 4' 30" E. Between 

 Marion Island and Prince Edward Island. 140 fathoms. Volcanic sand. 



Shell. — Rather thin, ovate, conical, translucent, umbilicated, with a large rounded tip, 

 convex whorls, an impressed suture, a short round base, a feebly varixed lip, and a 

 roundly oval mouth. Sculpture: Longitudinals — there are scratchy lines of growth, which 

 produce a very slightly reticulated surface. Spirals — there are on the penultimate whorl 

 from five to eight distinct rounded threads, separated by considerably broader furrows, the 

 shoulder below the suture is more or less free of these ; the entire surface is also finely 

 fretted with microscopic spiral striolations or scratches ; on the two embryonic whorls this 

 entire system of sculpture is replaced by a quite different set of very fine threads, with 

 somewhat broader furrows. Colour translucent white. Spire rather high, conical. Apex 

 large and rounded. Whorls 5 to 5^, rounded, of regular increase, but the last is a little 

 large. Suture rather broadly and shallowly impressed. Mouth open, roundly oval, 

 scarcely narrowed above. Outer lip sharp, with an extremely feeble and rather remote 

 varix. Inner lip thin, defined, and rather straight across the body, scarcely curved on 

 the pillar, where it is sharp-edged and patulous, with a smallish furrow, and a distinct 

 umbilical chink behind it. H. 009 in. B. 0-055. Mouth, height 0-039, breadth 0'03I. 



This species has a great general likeness to Rissoa moniziana, Wats., especially in sculpture, but 

 is larger, has a blunter apex, is umbilicated, and has a much thinner lip and a larger mouth. 



30. Rissoa {Ceratia) macra, 2 n. sp. (PI. XLV. fig. 10). 



Station 135c. October 17, 1873. Lat. 37° 25' 30" S., long. 12° 28' 30" W. Off 

 Nightingale Island, Tristan da Cunha. 100 to 150 fathoms. 



Shell. — Strongish, high and narrow, conical, subtransparent white, with a blunt sub- 

 truncated rounded tip, convexly conical-sided whorls, a very slightly impressed suture, 

 a convex base, a scarcely varixed lip, and a bluntly pear-shaped mouth. Sculpture: 

 Longitudinals — there are unequal lines of growth. Spirals — the whole surface is scored 

 with feeble flat threads, parted by very shallow somewhat broader furrows, faintly fretted 

 by minute microscopic semi-obsolete scratches. Colour translucent white. Spire very 

 high and narrow. Apex ending somewhat abruptly in a flattened rounded tip. Whorls 

 6, subconically convex, the last is long. Suture very slightly impressed, rather oblique. 

 Mouth bluntly pear-shaped, being broad below and narrowing upwards. Outer lip> sharp, 

 strengthened by a very feeble varix, patulous. Inner lip thin, but defined on the body. 



1 So called from the latticed sculpture. - fiax-i&s, long. 



