850 MR. T. H. WITHERS ON 



ridge extends from the apex to about the middle of the valve, 

 and is there met by two further ridges extending from each basal 

 angle ; the valve is thus divided into three almost equal portions, 

 the basal one being smooth and doubtless covered at one time by 

 the corium, the two upper portions being marked with growth - 

 lines and most probably overlapping the adjoining carino-lateral 

 valve on either side. 



Length (fig. 6) 5 mm. ; breadth 5"2 mm. 



Comparison with other Species. This species is referred to the 

 genus Scalpellum (sensu lata), a course that is advisable until we 

 can find the remaining valves of the capitulum, which may enable 

 us to refer the species to one of the subgenera into which 

 Scalpellum has been divided. Judging from the known valves 

 (carina, scutum, tergum, rostrum, and subcarina), this species is 

 related to S. zancleanum Seguenza * from the Pliocene of Messina, 

 Sicily. The carina of *S'. zancleanum- differs in having a strong 

 median keel, from which the sides of the valve slope steeply, and 

 in the less angular growtl^-lines ; the scuta differs in the rounded 

 basal margin and in the usually less acute tergo -lateral angle ; 

 the terga dififer in being inuch narrower in proportion to width, 

 in the much more acute apical portion, and in the carinal margin 

 not being divided into an upper and a lower portion; the rostrum 

 difiers in the absence of a wide, flat, median keel. 



Subgenus Arcoscalpellum. 



1907 (Oct.). Arcoscalpellum P. P. C. Hoek, Siboga-Expeditie, 



Cirripedia Pedunculata, p. 59. 

 1907 (Nov.). Holoscalpellum H. A. Pilsbry, Bull. No. 60, U.S. 



Nat. Mus. p. 25. 

 1908. Arcoscaljiellum Hoek; H. A. Pilsbry, Proc. Acad, Nat. 



Sci. Philadelphia, p. 109. 

 1912, Arcoscalpellum Hoek; T. H. Withers, Proc. Zool. Soc. 

 London, p. 538. 



Scalpellum (Arcoscalpellum) ungulatum, sp. n. (PI. LXXXYI. 

 figs. 7-13.) 



Diagnosis. Carina with its tectum almost flat, parietes more 

 than half the width of the tectum, intraparietes narrow and bent 

 abruptly inwards, basal margin rounded ; upper latera sub- 

 triangular, with rounded basal margin and wide lateral portions 

 obliquely inclined towards the umbo ; rostral latus with sub- 

 parallel scutal and basal margins, and about one-third of its 

 apical end, which is much thickened, projecting freely beyond the 

 scuta. 



* 1876. G. Seguenza, Atti Accad. Pontaniana, vol. x, p. 386, pi. vii, figs. 1-13. 



