272 MARINE INVERTEBRATES 
thicker than the other two. The abdomen is broad, covering the whole 
under side of the body, and is marked off with prominent raised ridges 
diverging from the center line. The legs are all beset with long, rough 
spines. Habitat, the northwest coast. Taken from the stomachs of fishes 
off Monterey, California. (Plate LXII.) 
SUBORDER BRACHYURA 
THE CRABS 
/ This group contains the true crabs, which are the highest of 
the Crustacea. In form they are quite the reverse of the first 
group. In the Macrura—except in the anomalous forms— 
the body is long and cylindrical and the abdomen extended, but 
in the Brachyura the body is flat and broad and the abdomen 
short and refiexed. Crabs of this suborder inhabit all seas of the 
globe, and are found from the shore to great depths. Some spe- 
cies live on land, some on the shore, some in deep water. Some 
forms burrow in the sand; others live under stones and boulders, 
or conceal themselves in crevices of rocks or in the cavities of 
sponges. They are divided into many families, and creep, climb, 
swim, or burrow, their structure being modified to their respec- 
tive modes of life. There is also great variation in their shapes 
as well as in their color and markings. This diversity isso great 
and peculiar that it seems as though each one were more curious 
than the others. 
In crabs the cephalothorax is depressed and often broader than 
long. The abdomen is relatively small and is folded under the 
thorax, lying in a groove which it fits so perfectly as to be quite 
hidden from above. The appendages of the abdomen are much 
reduced innumber. The male has two pairs; the female has four 
pairs, which it uses for carrying itseggs. The first pair of walk- 
ing-legs are comparatively large, and end in chele, or pinching- 
claws. The other eight legs terminate in simple points, except 
in the swimming varieties, when the fifth pair is flattened to form 
fins, or swimming-paddles. The eye-stalks are long and fit into 
sockets on the carapace. Both pairs of feelers are small. The 
antennules are frequently folded into small grooves. The exter- 
nal or third pair of maxillipeds are broad and flat, and cover the 
mouth-parts like a lid, or operculum. 
