CIRR1PEDIA 



3. — Verruca mitra n. sp. 



With four figures) 



Shell white, surface smooth, with prominent lines of growth and very distinct articulating 

 ridges. Wall formed by the hxed scutum and tergum nearly perpendicular to the surface of 

 attachment ; that formed by the rostrum, the carina and movable valves inclined and meeting 

 the hxed valves at a sharp edge ; base rather broad, oval. Movable scutum with two articular 

 ridges, apex pointed not projecting freely ; movable tergum also with two ridges and the apex 

 rounded. Rostrum and carina large, broad, so as to form part of the wall at the side of the 

 fixed scutum and tergum. Apex of the rostrum and carina projecting freely beyond the surface 

 of the shell, that of the carina distinctly recurved. 



This beautiful deep-sea species is represented by two spécimens, the one about three 

 times as large as the other. Though the smallest in nearly every regard resembles the larger, 

 for the description the latter is used especially. 



The surface of the shell is naked, there being no trace of a chitinous membrane. The 

 shell is beautifully white and looks as if it was eut out of ivory ; lines of growth on ail the valves 

 very distinct and the so-called articular ridges prominent. 



Seen from above the total shape of the shell is that of an oblique pyramid, inclining with 

 its tip towards the side of the hxed scutum and tergum and also towards that of the carina. As 

 the base of the shell is irregularly oval, the lower part of the pyramid is more like a flattened 

 conus ; but the upper part, when seen from above, shows three nearly flat sides : one formed 

 by the movable scutum and tergum, one by the rostral half of the fixed scutum and one by the 

 other half of that valve combined with the fixed tergum. Seen from the side of the movable 

 valves the shell is almost symmetrical and has a certain likeness to a cap or bonnet, the carina 

 and rostrum forming the wider under part, the movable scutum and tergum the conical central 

 part and the tip of the cap. 



Fig. i 



Verruca mitra, n. sp., seen from the side of the movable scutum and tergum. Magnified 10 diameters. 

 5 = movable scutum ; t = movable tergum ; r = rostrum ; c — carina. 



