REPORT ON THE GASTEROPODA. 198 



24. Nassa (Tritia) brychia, 1 Watson (PL XI. fig. 5). 



Nassa (Tritia) brychia, "Watson, Prelim. Report, pt. 13, Journ. Linn. Soc. Lond., vol. xvi. p. 365, sp. 3. 



Station VIII. February 12, 1873. Lat. 28° 3' 15" N., long. 17' 27' W. Off 

 Gomera, Canaries. 620 fathoms. Volcanic mud. 



Shell. — Strong, coarse, dirty white, ovate, rather stumpy, with a conical subscalar 

 spire, a small blunt apex, a round truncated base, a very short pillar, and scarcely any 

 snout. Sculpture : Longitudinals — the whorls are crossed by blunt, narrow, sparse, 

 sinistrally oblique riblets, which continue to the snout ; the last forms a strong varix on 

 the edge of the lip ; the lines of growth are fine, but towards the mouth become coarse. 

 Spirals — below the suture is a slight shoulder formed by a row of coarse, depressed 

 tubercles marking the upper end of the riblets ; on the upper whorls there are 2 to 

 3, on the body about 5, coarse, shallow furrows parted by broadish flat bands ; on the 

 base there are 6 of these furrows with narrower bands ; round the base of the pillar 

 winds obliquely a shallow furrow, with a slight sharpish band in front ; the short pillar 

 is scored with the old contorted canal-scars. Colour a dirty porcellanous yellowish 

 white. Spire rather short, conical, subscalar. Apex blunt and rounded, consisting of 

 3^ smooth, depressedly turbinate whorls, of which the tip is very small. Whorls 9, 

 conical, scarcely convex, not constricted below, with a short rounded base. Suture 

 marginated, and this margin tubercled. Mouth oval, open, bluntly pointed above. 

 Outer lip sharp on the edge, sparsely toothed, patulous, almost straight, slightly 

 advancing below, but not prominent on the base ; the canal has a slightly reverted 

 flange. Inner lip straight ; on the body it is a little hollowed into the pillar, which is 

 very short, and has in front a thickened (but not flanged) twisted edge ; the pad of glaze 

 is not thick, and has a sharply defined outer edge throughout its whole length. IT. 

 0-65 in. B. 0-37. Penultimate whorl, height 0-14. Mouth, height 0'35, breadth 0-2. 



This resembles Nassa reticulata, Lam., more than any other Atlantic form ; but, besides being 

 much smaller, the form of spire is much more scalar ; the ribs and spiral threads are much fewer, 

 and their intersections are flattened, not tubercled ; the callus on the lip is not indefinitely spread 

 on the body ; the junction of the pillar and the body is not so deeply furrowed ; and the front 

 of the pillar has no threads, only scars. It somewhat approaches a variety of Nassa trivittata, 

 Say ; but that has a much more conical, less scalar spire, with more rounded whorls ; the last 

 whorl is much less broad, is higher, is more extended in front, and is covered with raised rounded 

 threads. 



Mr Marrat, in his most curious and interesting study " On the Varieties of the Shells of the 

 Genus Nassa," p. 52, puts this species into a group very remote from either of the above. 



1 Pi v X'°'> belonging to the deep sea. 



