382 Dr. H. A. Nicholson on the Genus Climacograpsus. 
oe exhibited vary with the particular aspect of the 
processes. From C. antennarius, Hall (fig. 6), C. bicornis is 
C. tuberculatus, Nich., in which the characters of the base are 
5 e 
thicker and stronger, and are nearly or quite rectangular to 
radicle. 
The presence of a basal disk or cup in some forms of the 
species 1s a remarkable fact, since there can be little hesitation 
in comparing this to the corneous disk of some of the Dicho- 
grapsi and Tetragrapst. 
Loc. Skiddaw Slates (upper beds): Thornship Beck, near 
Shap. Lower Llandeilo: Penmorfa &c. Upper Llandeilo: 
Anthracitic Shales of Dobb’s Linn, Hart Fell, and Glenkiln 
Burn in Dumfriesshire. 
Climacograpsus antennarius, Hall. 
uc antennarius, Nicholson, Quart. Journ. Geol. Soc. vol. xxiv. 
This beautiful species has been fully described by Hall 
(Grapt. Quebec Group, p. 112, pl. 12. figs. 11-13), and was 
