2(54 RET. E. B. WATSON ON THE 



umbilicus, and rejoins the pillar-lip at the corner of the mouth. 

 Inner lip projects very slightly, is a little patulous, and leaves 

 behind it only a broad umbilical fissure. Across the body it is 

 hardly curved, and joins the outer lip almost at a right angle. 

 — H. 0-025. B. 0032. Mouth : H. 0021 ; B. 001 7. 



Common from Funchal eastward and at Porto Santo, deep water. 

 It does not seem to have been observed by any one but myself. 



If the shell be really nacreous, the layer of nacre must be so 

 transparently thin as to give no opalescent reflection. The 

 species is very like S. tabulata, Wats. (' Challenger ' Grasterop. 

 p. 117, viii. 7), but is very much smaller in all its dimensions, 

 especially in height of spire ; in spite, too, of superficial resem- 

 blances, it differs in sculpture, the riblets being here much fewer 

 and feebler and more curved, the canal-keel aud respiratory hole 

 lie much nearer the suture, the spirals are feebler, the last 

 whorl too is larger and not so much contabulated. It should be 

 noted how deceptively different the adolescent is from the full- 

 grown shell. 



This is the shell a hasty identification of which from my speci- 

 mens led Dr. Gwyn Jeffreys to quote Scissurella costata, d'Orb., 

 for Madeira. 



Tarn. Eetcinidje. 

 GTen. Montacuta, Turt. 



33. MONTACUTA TRIANGULARIS, U. Sp. 



Shell triangularly round but not at all rhomboidal, some- 

 what tumid, strongish but almost transparent, bright but not 

 brilliant. Sculpture fine, close-set, somewhat unequal concentric 

 lines of growth. Colour clear white. Epidermis, none visible. 

 Margin rotundly oval but for the upward and backward promi- 

 nence of the beaks ; the edges of the valves meet directly with 

 very little expansion at coming together. Beaks small, rounded, 

 sufficiently prominent to give a triangular aspect to the shell ; they 

 are somewhat nearer the back end of the shell, towards which but 

 still more upward they slightly turn. Hinge-line broken into a 

 right angle by the beak ; the edge is long and very narrow in 

 front, behind it is comparatively very short and broad. Hinge- 

 plate has a deep triangular cleft from the interior of the shell to 

 the beak ; in the right valve on either side of this cleft there 

 rises a solid little rounded tooth ; in the left valve the cleft is 



