45 b' THE VOYAGE OF H.M.S. CHALLENGER. 



This species has so strongly the aspect of Natica islandica, Gm. (= helicoides, Johnston = cana- 

 liculata, Gd. = cornea, Moller, out of which and the two latter synonyms Messrs Adams form their genus, 

 which is Morch's subgenus Amauropsis, characterising it by a feature which the species has not, 

 viz., the absence of an umbilicus), that I can easily believe connecting links will yet establish their 

 identity. The age of Natica islandica and its distribution, as well as its present habitat in Subarctic 

 and Arctic seas, make its presence in Antarctic regions more probable. But for the present it is 

 impossible to unite them. Natica suturalis has an epidermis which, though minutely marked very 

 much like that of Natica islandica, is coarser, darker-coloured, and more fibrous ; the form of the 

 shell is broader ; the spire is lower, less scalar, with a less deeply channelled suture ; the mouth is 

 much rounder and is less pointed below. Dr Gwyn Jeffreys considers this species to be Natica 

 groenlandica, Beck, var. pallida, Brod. and Sow. There are specimens of that species which present 

 much the same epidermis and some which have an unusually high spire, but I have seen none 

 approaching this species in the excess it presents in the latter feature, nor is the suture ever so 

 channelled ; in Natica pallida, too, there is always a contraction of the outline below the suture, 

 which is quite absent here ; and in that species the inner lip is very much thicker. 



Family Capuloidea, Cuvier, 1830. 



Genera. 1. Capulus, Montf. 2. Amalthea, Schum. 3. Crepidula, Lam. 

 4. Ccdyptrxa, Lara. 5. Mitrularia, Schum. 



1. Capulus, Montfort, 1810. 

 Species. 



1. Capulus japcmicus, A. Ad. 2. Capulus (Amathina) tricarinatus (Linne). 



1. Capulus japonicus, A. Adams. 



Capulus japonicus, A. Adams, Ann. and Mag., 1861, ser. 3, vol. viii. p. 138, sp. 1. 

 „ „ Dunker, Index MolL Mar. Japon., p. 124. \ 



March 7, 1875. Admiralty Islands, north-east of Papua. 1G to 25 fathoms. 

 Habitat. — Mino Sima, Japan (Adams). 



2. Cajmlus (Amathina) tricarinatus (Linne). 



Patella tricarinata, Linne, Syst. Nat. (ed. 12), p. 1259, No. 764. 



„ tricostata, Gmelin, Syst. Nat., p. 3698, No. 27, and (as Patella tricarinata) p. 3710, No. 92. 

 „ „ Chemnitz, Conch. Cab., vol. x. p. 333, pi. clxviil figs. 1622, 1623. 



,, tricarinata, Dillwyn, Cat, voL ii. p. 1039, sp. 52. 

 „ ,, Wood, Ind. Test., p. 187, pi. xxxvii. fig. 51. 



,, tricostata, Lamarck, Anim. s. vert., vol. vi. (1) p. 335, and (ed. Desh.) vol. vii. p. 540, sp. 43 

 (in note Pileopsis tricarinata). 



