POLLICIPES. 75 



closely related to each other, and in a far less degree to P. dorsatus. Some remarks on 

 tlieir diagnostic characters will be given under the two following species. All three species 

 are remarkable by the peculiar form of their scuta, which have so much resemblance (espe- 

 cially in P. rigidus) to the terga of other cirripedes, that until I examined their under 

 surfaces I was not sure which valves they were. The conspicuous ridges running obliquely 

 downwards from the apices of the scuta and terga, I have little doubt were due to the carina 

 and rostrum largely overlapping these valves, and to the presence of large upper latera, so 

 that the lower angles of the scuta and terga were closely wedged between these valves. 



19. POLLICIPES FALLAX. Tab. IV, fig. 8. 



P. valvis trayisverse costatis : scutis, margine basali non recto, anguliim 2J(sne rectum 

 cum margine occludente formante ; costd, parietibus obliquis, ab apice ad angulum baso-late- 

 ralem decurrente : tergis, costd curvatd, parietibus obtiquis, ad angulum basalem latum, 

 rotundatum, decurrente. 



Valves transversely ridged. Scuta, with the basal margin not straight, forming nearly 

 a right angle with the occludent margin ; a ridge having sloping sides runs from the apex 

 to the baso-lateral angle. Terga, with a curved ridge having sloping sides, runs to the 

 broad, rounded basal angle. 



Upper Chalk, Norwich. Mus. Fitch. Maiistricht Formation, Balsberg and Kopinge, Scania. Mus. 

 Univers. Copenhagen. Oberer Kreidemergel (Upper Chalk), Gehrden in Hanover. Mus. Roemer. 



The specimens which I have seen, consist of three right-hand scuta and one tergum, in 

 the possession of Mr. Fitch, from Norwich ; of two scuta and two terga collected by M. 

 Angelin, in Scania, and forwarded to me by Professor Steenstrup, and of a scutum from 

 Hanover, sent to me by Roemer, together with specimens of his P. unclnatus. 



Description. The valves are moderately thick ; they are conspicuously marked with 

 rather wide prominent ridges, forming the basal edges of each zone of growth ; they seem 

 in both scuta and terga most strongly developed near the occludent margins. 



Scuta (fig. 8, a) almost triangular, moderately convex ; occludent margin considerably 

 arched in the upper part, and bowed towards the terga; basal margin not straight, v^^ith 

 a short portion close to the rostral angle forming a rectangle with the occludent margin ; 

 the remaining portion, if produced, would form a rather larger angle with it ; hence the 

 baso-lateral portion of the whole valve is somewhat protuberant. The tergo-lateral margin 

 is in the upper part slightly hollowed out, and in the lower part almost straight. A very 

 slightly curved ridge runs from the apex to the baso-lateral angle, which is broad, rounded, 

 and not prominent ; the ridge has sloping, not wall-like sides. Internally the structure of 

 the upper part closely resembles that of P. rigidus. The furrow on the tergal side is rather 



