some new and peculiar Mollusca. 319 



Europe and America, and indicative of glacial conditions ; 

 it has a vertical ran^^e of 1840 feet. 



This species varies considerably in tiie comparative lieiglit 

 of the sj)ire 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 

 ly'^in breadth ; another specimen, from Spitzbcrgen, is nearly 

 as large. N. russa of Gould is ap])arently a variety also 

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

 Sowerby ; ^V. co7isolidata, Couthouy ; iV. septentrionalis 

 (Beck) , MoUer ; and N.janthostoma, Deshayes. I have taken 

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

 somewhat differ. 



A very young shell of another species of Xati'ca occurred in 

 Station D, 17o0 fms. It resembles the fry of A^. grcenlandica, 

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

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

 named spkceroidei: 



Solariidae. 



Seffiienzi'a formosa* , Jeffr. 



Scffitenzia furmosa, Proc. Koy. Soc. vol. xxv. no. 173, pp. 200, 201 

 (woodcuts). 



Shell globosely conical, rather thin, semitransparent, 

 nacreous and glossy : sculpture^ 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 striae, which 

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

 character to this part of the sculjtture ; the strias between the 

 infra.sutural and peri])heral rib turn to 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 striae on the base of the last whorl ; these 

 strise 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 : sjrire 

 turreted : ichorls 7, somewhat convex, gradually enlarging ; 

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



* Beautiful. 



