some new and peculiar Mollusca. 241 



ScalariidsB. 



Acirsa EscJirichti, Holboll. 

 Scalaria Eschiichti (Holb.), Moller, Ind. Moll. Groenl. p. 10, 



Station 4, 20 fras. Greenland (Holboll, Barrett) ! Spitz- 

 bergen (Torell) ! Murray Bay, Canada (Dawson). Eastport 

 (Verrill). Newfoundland (Verkrlizen) ; a fragment! Fossil: 

 coasts of Antrim and Aberdeenshire ; Uddevalla ; Canada 

 (Bayfield,/c^eLyell)? 



In my list of species which I considered Greenlandic, but 

 not North-American nor European (' Proceedings of the Royal 

 Society,' vol. xxv. no. 173, pp. 193 and 194), I included 

 this species from an oversight. It is both North-American 

 and European. Morch regarded his Acirsa as a subgenus of 

 Scalaria ; but I would venture to raise it to generic rank, for 

 the following reasons. The lips of the mouth in Acirsa are 

 not continuous and thickened, so as to form a peristome ; the 

 apex of the spire is blunt, instead of being finely pointed ; and 

 the peculiar variciform ribs of Scalaria are wanting. 



Herr Weinkauff's collection of Algerian shells contains a 

 ribless and worn specimen of Scalaria crenata, Linne, which, 

 at first sight, looks like Acirsa Eschrichii, and was mistaken 

 by the Marquis de Monterosato and myself for that shell (see 

 his ^ Notizie intorno alle Conchiglie Mediterranee,' page 40, 

 and the ' Journal de Conchyliologie ' for January 1877, p. 38) ; 

 but on closer examination I find that tlie lips of the mouth 

 in the Algerian shell are thickened and continuous, the whorls 

 are convex instead of compressed and somewhat angulated at 

 the base, and it shows traces of the punctate sculpture and 

 infrasutural notches which are peculiar to S. crenata. 



Synonyms : S. horealis^ Beck (1839), probably, but without 

 description; S.undata^ Sowerby; Turritellahibernica^Y^aWex. 

 S. suhdecussata of Cantraine [Mesalia striata^ A. Adams) 

 belongs also to the genus Acirsa. 



Acirsa prcelonga '^ ^ JefFr. 



Shell having the shape of a long and graceful obelisk, 

 rather solid, opaque, when living probably glossy : sculpture, 

 numerous fine, curved, longitudinal striaj or riblets, and 5 

 thread-like spiral stride on each whorl ; of these last the 

 bottom or suprasutural stria is the strongest and forms a keel 

 round the base, which is smooth and somewhat excavated ; 

 the part below^ the suture (about one third of each whorl) is 

 also destitute of spiral striae ; in one specimen the uppermost 



* Very long. 



