the Cirripede Subgenus Scillelepas. 261 
margin very slightly convex, almost straight, not divided 
into an upper and a lower portion ; occludent margin gently 
convex, almost straight, and forming with the carinal margin 
an angle of about 35° ; scutal margin slightly convex, rather 
longer than the oecludent margin, with which it makes a 
rounded angle. ‘lhe valve is ornamented similarly to the 
carina, but the longitudinal lines are more apparent. 
Subcarina more than half as wide as long, not nearly so 
strongly convex as the apical portion of either of the two 
carine ; basal margin slightly convex. The inner surface of 
the valve slopes towards the outer surface and forms a sharp 
edge, so that there is no possibility of this valve being merely 
the broken off apical portion of a carina. 
Systematic Position of Calantica (Scilleelepas) gaveyi. 
Darwin, in his Monograph (1851), referred the known 
Jurassic species (Pollicipes concinnus, Morris *, P. ooliticus, 
Buckman J, and P. planulatus, Morris t) to the genus Polli- 
cipes. Now the distinguishing characters of Pollicipes, which 
is essentially a recent genus, and evidently a polyphyletic 
one, is the downward growth of the valves, and their large 
number (from eighteen to over one hundred). Certainly the 
valves of the above three species have a downward growth, 
and since there is evidence in only one species —P. concinnus 
—that the valves numbered more than eighteen, Darwin must 
have relied on the downward growth of the valves, and 
almost as certainly on the distinctive characters of the detached 
valves as compared with those in the genus Sca/pellum. 
Scalpellum has more modified valves, numbering from twelve 
to fifteen. 
Two further genera have since been established which 
embrace Jurassic species—namely, Archwolepas, Zittel § 
(1884), and Pycnolepas, Withers || (1914), the former in- 
cluding the species Pollicipes redtenbachert, Oppel, Pollicipes 
royeri, de Loriol, and’ Pollicipes quenstedti, von Ammon, and 
- the latter including certain Cretaceous species, together with 
* Morris, J., 1845, Ann. & Mag. Nat. Hist. ser. 1, vol. xv. p. 30, pl. vi. 
fic. 1; Darwin, C. R., 1851, Pal. Soc. Monogr. Lepadide, p. 50, pl. iii. 
hig. 3, 
“+ Buckman, J., 1844, Geol. Cheltenham, p. 95, pl. iii. fig. 7; Darwin, 
C. R., 1851, Pal. Soc. Monogr. Lepadide, p. 50, pl. iii, fig. 2. 
t Morris, J., 1845, op. cit. p. 31, pl. vi. fig. 2. 
§ Zittel, K. A. von, 1884, Sitzungsb. k. b. Akad. Wiss. Miinchen, 
Bd. xiv. Heft iv. p. 581. 
|| Withers, T, H., 1914, Ann. & Mag. Nat. Hist. ser. 8, vol. xiv. 
pp. 170, 200. 
