18 Alf Wollebæk. [No. 12 
FHiconaxwus acutifrons Sp. B. 
(SPpENcE Barr, Chall. Ex. Vol. XXIV). 
Maxilliped Pereiopod 
2nd | 3Srd lst | 2nd | 3rd | 4th | Sth 
= 
Arthrobranchiae LASSE 0 Og 2 2 2 2 0 
Podøbrancuae AEE 0 1 1 1 1 0 0 
Mastigobranchiae ......-.... 1 1 1 1 1 1 0 
Parazxius altus Sp. B. 
(SPENCE BATE, Chall. Ex. Vol. XXIV). 
Arthrobranchiae da 0 2 2 2 2 2 0 
Podobrancenne 0) 1 1 1 1 0 0 
Mastisobranemaer FLERE 1 1 1l 1 il il 
| 
Calastacus. 
(Faxon, Report on the Dredging ete.). 
Arthropbranedmac EEE 0 2 2 2 2 2 0 
Podobrinemae 1 1 1 1 0 | 
Mastigobranchiae .......s.. 1 1 Å 1 1 il 
1st Pereiopod. The chela of the right pereiopod is generally 
much more stoutly developed than the left; and it is mainly 
owing to the difference in structure and size of the larger eclaw 
that Trysom has classified UC. crassipes as å different species 
from OC. coronatus. In the latter this limb is much weaker and 
more flattened, has å comparatively longer and thinner chela, with 
less eurved digits than we find in U. crassipes. In UC. erassipes the 
ehela is about the length of the carapace without the rostrum, 
whereas in OC. coronatus it is only a little longer than half the 
length of the carapace including the rostrum. 
1st Pleopod was wanting in all the specimens of males 
examined, but was present in both the females. This quite agrees 
with what Speznce Batz has found in Eiconazxius acutifrons: "rudi- 
mentary in the female, and appears to be wanting in the male.” 
