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There are spines with one or two specimens only, there are others with 5 or 6 or more 

 specimens, and there is even a spine with 1 2 specimens attached to it. 



This species seems to range over a considerable depth : there are specimens found at 

 450, 520 and 984 m. 



5. Vcrrtica conchtila n. sp. PI. XI, fig. 14 and 15. 



Shell not depressed, plan of the moveable valves in the same direction as that of rostrum 

 and carina. Moveable tergum with three articular ridges, scutum also with three articular ridges 

 as well as three prominent ridges betvveen its axial ridge and its occludent margin. Carina 

 small, with the apex projecting freely ; rostrum large, with numerous and very prominent 

 ridges, cup-shaped, turned over with its base to the side of the fixed valves. Fixed scutum 

 laterally turned over to the side of the moveable valves. 



This beautiful but curious species is represented by a single specimen only. It is a 

 small shell, the largest diameter being under 6 mm. It is loose and has been attached, to judge 

 from the form of its base, laterally against a cylindrical object, part of the outer surface of 

 which is still to be seen adhering to the membrane representing the basis. The colour of the 

 shell is dirty white, yellowish. It is recognisable at once by the numerous and prominent ridges, 

 or ribs with rounded surface, especially on scutum and rostrum, and also on part of the fixed 

 scutum and the carina (PI. XI, fig. 14). The whole shell has an irregular globular shape r 

 but the rostrum particularly is very distinctly convex, markedly bent over to the side of the 

 fixed valves. 



The moveable scutum is relatively small, triangular, with the occludent margin very 

 strongly convex, the basal margin nearly straight but having three excavations, in which fit the 

 extremities of as many ribs of the rostrum, and the tergal margin irregularly toothed and with 

 excavations between the teeth. Besides the three ordinary, true articular ridges, the third of 

 which is more strongly developed and represents the axial ridge, the surface of the scutum 

 shows three other longitudinal and rather prominent ridges on that part which is between the 

 axial ridge and the occludent margin. Of the articular ridges, the first extends to about the 

 middle of the tergal margin, the second to where it meets the main articular riclge of the 

 tergum, and the third to the basi-tergal angle of the valve. 



The moveable tergum is rhomboidal in shape, and distinctly, though not sharply 

 beaked. The longest occludent margin is convex, the shortest hollowed out, the scutal margin 

 irregularly toothed, the basal margin straight. The part of the surface between the main articular 

 ridge and the convex occludent margin shows distinct lines of growth running parallel to the 

 basal margin ; the rest of the surface is occupied by the three articular ridges : the main or 

 axial, which is strongly convex and runs from the apex till the basi-scutal angle, the middle 

 ridge, which is broad and also convex, and the first, which runs along the occludent margin 

 and can hardly be distinguished from it. 



The carina is rather small and has the apex projecting beyond the basi-carinal angle 

 of the tergum. Its shape is triangular; its tergal margin is straight, the margin forming the 



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