Prof. W. B. Benham — A Giant Fossil Cirripede. 117 



to is attributed to the genus PolUcipes, viz. P. reflexus (see pi. iii, 

 figs. 8a-c). In this species, as in one or two others, the lines of 

 growth, and therefore the base itself, are transverse and straight ; the 

 parietes are seen from above, and, though not precisely like those of 

 the present fossil, yet bear a closer resemblance to it, in possessing 

 a slight angle on its margin, than do those of any of the species of 

 Scalpellum ; while the inclination of the parietes to the tectum, as 

 represented in the transverse section, is also similar, as is the 

 general direction of the lines of growth, though the angulation 

 of these, which occurs in our fossil, does not appear to exist. It 

 is, moreover, the only Tertiary PolUcipes described in the monograph, 

 having been found in the ' upper marine Eocene ' at Colville Bay, 

 Isle of Wight. 



The scutum : in its greatly elongated and much narrowed form 

 this valve is quite unlike that of any of the fossil species either of 

 Scalpellum or of PolUcipes figured by Darwin ; but among living 

 species Sc. album, Hoek,^ has a very similar valve, so far as its general 

 proportions are concerned. But what seems to distinguish our 

 valve as much as any other feature is the very marked inflexions 

 of the tergo-lateral region ; in most of those figured by Darwin 

 this ' flange ' appears to lie very nearly in the same plane as the 

 ' chief plate ' itself ; although in the description of some of the 

 species, e.g. Sc. arcuatum and P. Angelini, he states that the "tergo- 

 lateral portion is inflexed." 



Darwin, in his diagnosis (p. 17) of Scalpellum, says, " scuta very 

 slightly convex, four-sided, tergal and lateral margins being divided 

 by a slight angle " ; whereas PolUcipes (p. 48) possesses scuta which 

 are " generally three-sided, but sometimes, either from the baso- 

 latei'al or rostral angle being truncated, there is an additional side. 

 The tergo-lateral margin is either straight or, generally, more or less 

 convex, but it is never divided into two distinct margins." 



Now, if our scutum be examined merely from the outside, the 

 tergo-lateral margin is scarcely angulated, and the general outline 

 (except for its great elongation) resembles the scutum of P. Angelini 

 or P. acuminatus much more nearly than it does any of the figures 

 of Scalpellum. If, however, it be viewed from the side there is 

 a more distinct angle, but even this is not so pronounced as in 

 Scalpellum, in which the part that I have termed ' flange ' appears to 

 be less differentiated than in our species or in the genus PolUcipes. 

 On the whole our valve seems to agree rather with that of P. Angelini 

 than with any other fossil Cirripede. In his description of the 

 scutum of this species Darwin writes (p. 57) : " The tergo-lateral 

 portion of the valve, formed by the upturned lines of growth, is 

 not much developed ; the tergo-lateral margin, as seen externally, 

 is obscurely divided into two lines, of which the upper or tergal 

 portion has its edge reflexed." 



In reference to the other two valves described, very few words 

 are necessary. The one which I suggest is ' rostrum or sub-carina ' 

 is, like our other valves, much narrower than in other species, either 



^ Hoek: "The Cirripedia (Systematic Part)," Ghallenffer 'Rej^oits, 1883, viii. 



