some new and peculiar Mollusca. 319 



Europe and America, and indicative of glacial conditions ; 

 it has a vertical range of 1840 feet. 



This species varies considerably in the comparative height 

 of the spire and in the angularity or compression of the whorls 

 below the suture. The variety occlusa attains a large size, 

 one of my specimens measuring 1^^ inch" in length, and 

 lyo in breadth ; another specimen, from Spitzbergen, is nearly 

 as large. N. russa of Gould is apparently a variety also 

 of N. affinis. The synonyms are : — N, clausa, Broderip and 

 Sowerby ; N. consolidata, Couthouy ; N. septentrionalis 

 (Beck) , Moller ; and N.janthostomaj Deshayes. I have taken 

 the descriptions of the animals from my note-book; they 

 somewhat differ. 



A very young shell of another species of Natica occurred in 

 Station 9, 1750 fms. It resembles the fry of N. groenlandica^ 

 but has one whorl less, the last is more expanded, and the apex 

 is flattened. Should an adult specimen be found, it might be 

 named sphceroides. 



Solariidae. 



Seguenzia formosa *, JefFr. 



Segumzia formosa, Proc. Roy. Soc. vol. xxv. no. 173, pp. 200, 201 

 (woodcuts). 



Shell globosely conical, rather thin, semitransparent, 

 nacreous and glossy : sculjpture^ sharp keel-like spiral ribs or 

 ridges, of which there are two on the middle of the body- whorl 

 (besides ten thread-like riblets on the base) and one on the 

 middle of each of the other whorls ; there is also a slighter 

 rib immediately below the suture ; between the ribs the sur- 

 face is covered with numerous and delicate curved stride, which 

 turn alternately in different directions, so as to give a flexuous 

 character to this part of the sculpture ; the striae between the 

 infrasutural and peripheral rib turn fo the left, while those 

 between the peripheral and the next rib (or in the upper whorls 

 between the rib in the middle and the base) turn to the right ; 

 the same alternate order is to a great extent observable as to 

 the direction of the striee on the base of the last whorl ; these 

 striae are crossed by fine close-set spiral lines, producing a 

 reticulated appearance ; all the whorls are similarly sculptured 

 except the top whorl or apex, which is smooth : colour 

 pearly-white : suture marked by the uppermost rib : s])ire 

 turreted : whorls 7, somewhat convex, gradually enlarging ; 

 the last takes up three fifths of the shell ; apex globular : 



* Beautiful. 



