666 
being just behind the excurrent gill opening. 
Eucorystes and 
from the Gault to Eocene. 

Fic. 1397. ns 
: : - 1398. 
Palaeocorystes Stokesi, Hire, A636 
Mant. sp. Upper Necrocarcinus tricarinatus, 
Bell. 
bridge, England (after Bell). 
Greensand; Cam- 
bridge, England. 
maxillipeds (buccal frame) are quadrilateral in outline. 
Micromaia, Bittner (Fig. 1399), and 
Microthoraz, Noetling, are Eocene and 
Miocene respectively. Lambrus, Leach, 
is Eocene and Recent. 
(5) The Cyclometopa (Cancroidea) 
have a broad carapace, arcuate in front 
and narrowed behind, without prominent 
rostrum. The tribe is subdivided into 
the swimming crabs (Portunidae) and 
shore crabs (Cancridae), the former being 
distinguished by their lamellate feet, the 
fifth pair terminating in a broad flattened 
paddle. To the first group belong Nep- 
tunus and Achelous, de Haan; Charybdis, 
Dana ; Portwnites, Bell ; Psammocarcinus, 
M.-Edw. (Fig. 1400), ete, which make 
their appearance in the Eocene. The 
Cancridae are older ; Palaeocarpilius, M.- 
ARTHROPODA 
Greensand; Cam- 
SUB-KINGDOM VII 
Palaeocorystes, Bell (Fig. 1397), ranges 
Necrocarcinus, Bell (Fig. 1398), are Cre- 
taceous ; Hepatiscus, 
Bittner, is Eocene ; 
Calappa and Ma- 
tuta, Fabr., range 
from Eocene to 
Recent. 
(4). In ‘the 
Oxyrhyncha, or tri- 
angular crabs, the 
cephalothorax is 
broad behind, 
pointed in front, 
and the external 
Fossil forms few and small. 

Fic. 1399. 
Micromaia tuberculata, 
Bittner. Eocene; San 
Giovanni Illariene, Italy 
(after Bittner). 

Fic. 1400. 
Psammocarcinus Hericarti, Desm. sp. Middle Meeres- 
sand (Miocene); Le Gué-a-Tresmes, France (after A. 
Milne-Edwards). 
Edw., appearing in the Upper Cretaceous and Eocene; and Panopaeus, M.-Edw., 
is 
Fic. 1401. 
Lobocarcinus Paulino-Wiirtembergicus, v. Meyer. 
near Cairo, Egypt. Male. 

Eocene ; Mokkatam, 
ranging from Cretaceous to 
Recent. Harpactocarcinus, 
M. - Edw.; Lobocarcinus, 
Reuss (Fig. 1401); Xan- 
thopsis, M‘Coy (Figs. 1402, 
1403), are very abundant. 
in the Eocene; Afergatis, 
de Haan, in the Oligocene ; 
Xantho and Cancer, Leach, 
in the Neocene. Neptocar- 
cinus and Cuarcinocarcinus, 
Lérenthey, are described 
from the Eocene of Hungary 
and Bavaria respectively. 
(6) The Catometopa have 
the carapace quadrilateral 
in outline, the front being abruptly truncated or slightly arcuate, and the sides nearly 
straight and converging behind. 
Galenopsis, Coeloma, M.-Edw. (Fig. 1404) 
Living species are marine, fluviatile, or terrestrial. 
; Litoricola, Woodw.; and Palaeograpsus, 
