300 ZOOLOGY. 
The arrangement of the ventral system of arteries 1s very 
peculiar and quite characteristic of this animal. The ceso- 
phageal nervous ring, and in fact the entire nervous cord, is 
ensheathed in a vascular coat, so that the nervous system 
and its branches are bathed by arterial blood. The veins 
are better developed than usual ; there being in the cephalo- 
thorax two large collective veins along each side of the in- 
testine. 
Closely connected with the two large collective veins are 
two large brick-red glandular bodies each with four branches 
extending up into the dorsal side of the cephalo- -thoras. 
They are probably renal in their nature. 
Both the ovaries and testes are voluminous glands, each 
opening by two papille on the under side of the first ab- 
dominal feet. At the time of spawning the ovary is greatly 
distended, the branches filled with green eggs. 
Unlike most Crustacea, the female king-crab buries her 
eggs in the sand between tide-marks, and there leaves them 
at the mercy of the waves, until the young hatch. The eggs 
are laid in the Northern States between the end of May and 
al 
Fic. 266, Fig. 267. 
Fig. 266._Embryo of King-crab, enlarged ; am, serous membrane ; ch, chorion. 
Fig. 267.--The same, more advanced. 
early in July, and the young are from a month to six weeks 
in hatching. 
After fertilization the yolk undergoes total segmentation, 
much as in spiders and the craw-fish. When the primitive 
disk is formed the outer layer of blastodermic cells peels off 
soon after the limbs begin to appear, and this constitutes 
