1885.] 'lightning' AND 'porcupine' KXPEDITIONS. 45 



but Fischer de Waldheim's name of Xenophora has the priority of 

 three years over that of Montfort. 



The apex of the shell forms a short but compact cone of several 

 smooth whorls. 



Family XXIV. Vklutinid.e. 



1. Lamellaria perspicua, Linne. 



Helix per spicua, L. S. N. p. 1250. 



L. perspicua. B. C. iv. p. 235, pi. iii. f. 6 ; v. p. 235, pi. Ixxix. 



f. 2. 



'Porcupine' Exp. 1870: Atl. St. 26; Med. Rasel Amou?h, Gr. 



Tunis. , , „ 



Distribution. Norway, Faroe I., Great Britain and Ireland, Brest 



{Daniel), Atlantic coasts of France and Spain {Hidalgo), throughout 



the Mediterranean and Adriatic, Canaries {McAndrew), Labrador, 



Canada, United States ; 0-108 fms. 



Fossil. Pliocene : Coralline Crag, Monte Mario, Calabria, and 



Sicily. 



Bulla haliotoidea and Lamellaria tentaculata, Montagu, Marsenia 

 producta and complanata. Leach, Siyaretus vitreus, O. G. Costa, and 

 S. audouinii, Cantraiue ex typo. 



2. Lamellaria tenuis', Jeffreys. (Plate V. figs. 5-5 b.) 

 Shell nearly circular in outline with a concave base, thin and 



fragile, semitransparent and glossy : sculpture, extremely delicate, 

 close-set, and microscopic spiral striae ; these are sometimes wanting 

 on parts of the surface : colour clear white : spire small, laterally 

 placed and depressed : %vhorls 2|, rather convex ; the last occupies 

 five sixths of the shell ; the first or apical whorl is sunken, in- 

 complete, and twisted inwards : suture narrow, but deep : mouth 

 nearly round and expanding: outer lip projecting above the 

 periphery, and forming at the base a short and slightly reflected 

 pillar : inner lip none : umbilicus small, but distinct and deep. 

 L. 0-1, B. 0-15. 



'Porcupine' Exp. 1870: Atl. St. K>. Four specimens. 



It differs from Sigaretus excavatus of Searles Wood in shape, the 

 spire, and the umbiUcus, as described and figured in his Monograph 

 on the Crag Mollusca. 



This delicate little shell appears to be internal and completely 

 enclosed within the mantle of the animal, because of its fragilit}^ the 

 incompleteness of the nucleus, and its not having any trace of an 

 epidermis, which is conspicuous in Sigaretus striatus or /> alio toideus. 

 But the distinction between Lamellaria and Sigaretus is not so well 

 defined as could be wished. The chief difference consists in the 

 presence or absence of an operculum. The sculpture of the present 

 shell resembles that of certain species of Philine. 



1 Thin. 



