POLLICIPES. 59 
mens, consisting of a scutum, terga, carine, and upper latera; and to Mr. F. E. Edwards 
the loan of several very perfect specimens. 
Valves ; smooth, rather thin. Scutum (fig. 8, e) elongated, very slightly convex, many- 
sided, almost oval, with its upper point produced, but apparently apt to be broken off. 
Occludent margin slightly arched; basal margin consists of two sides, of which the rostral 
side is extremely oblique to the other, the two sides together forming a very large angle 
with the occludent margin; the tergo-lateral margin also consists of two sides, meeting 
each other at a very open angle; the lower half forms above a rectangle with the basal 
margin; possibly this lower half corresponds with the widely-truncated baso-lateral angle 
in P. dorsatus, and with the smaller similar angle in the tertiary P. carinatus. A faint 
rounded ridge runs from the apex to the baso-lateral angle, and thus divides the valve into 
two nearly equal halves. Internally there is a deep pit for the adductor muscle ; only a 
narrow internal edge along both sides of the apex is marked by lines of growth. 
Terga (fig. 8, d); elongated, rhomboidal, flat and thin; carinal margin continuously 
curved; apex much produced; the occludent and upper carinal margins meet each 
other at much less than a right angle; occludent margin slightly longer than the scutal 
margin, which latter in the upper part is very slightly hollowed out; a faint, rather wide 
ridge, runs down the centre of the valve to the rectangularly-pointed basal angle; a small 
portion of the upper part of the terga projected freely. 
Carina (fig. 8, a, 6, c); narrow, with the lower part somewhat spear-shaped ; almost 
straight, transversely convex, with the central part forming a broad rounded crest ; lateral 
margin a little inflected; basal margin extraordinarily produced, with its apex square ; 
internally, the corium-covered surface is produced upwards into the sharpest apex; a 
small portion only of the uppermost part of the valve projected freely. 
Upper Latera (fig. 8, f) ; flat, almost pentagonal, with the two upper margins consider- 
ably longer than the three lower ones ; of these three, the carinal margin is the shortest, and 
the other two equal, with the rostral one considerably arched or convex; these three basal 
margins must have been in contact with the Latera of the lower whorl; the apex did not 
project freely. I have not seen any latera of the lower whorl, but Mr. Sowerby gives 
figures of some minute valves, which no doubt were such. Several of Mr. Edwards’s speci- 
mens are tinged a pale-reddish purple. 
Dimensions. 'The valves described are all rather small; the largest, a tergum, is a little 
more than a quarter of an inch in length. 
Affinities. This species is more nearly related to the section of the genus containing the 
recent P. cornucopia, elegans, and polymerus, than to the other sections. Its affinity is 
closest to P. cornucopia, though in the form of the basal margin of the scuta there is more 
resemblance to P. polymerus. The scutum presents some points of resemblance to the 
cretaceous P. gracilis and dorsatus. 
