GENERAL ANATOMY OF A CRAB. 193 



of the surrounding organs. This hollow usually contains, 

 in the female, a portion of the orange-yellow ovary 

 (Fig. 100, /*), and underneath this the tubular, trans- 

 parent, convoluted, intestinal coecum (Fig. 100, <?), which 

 consists of two portions, a long, very small tube, which 

 is twisted into a compact ball, a little to the right of the 

 middle line, and a larger portion which is nearly straight, 

 and runs backwards on the left of the middle line, into 

 the first segments of the abdomen, where it opens into the 

 intestine. 



/. Below the intestinal coecum, portions of the light 

 grayish-yellow liver may usually be seen ; and if the pos- 

 terior free ends of all these organs are gently raised up, 

 the transparent, straight intestine may be seen running 

 backwards into the abdomen on the middle line below 

 them. 



m. These organs and the pericardium are bounded 

 laterally by elevations which reach nearly to the dorsal 

 carapace, and are encased in a hard, white, calcified shell. 

 They are known as theflancs (Fig. 100, n), and they con- 

 tain the muscles of the pereiopods. Their inner edges are 

 nearly vertical, and form the walls of the depression for 

 the heart and intestinal coecum, while their outer surfaces 

 slope gently downwards and outwards. 



n. The outer sloping surface of each flanc is covered by 

 the tough, transparent chitinous wall (Fig. 100, &) of the 

 branchial chamber, through which the long, pyramidal 

 gills (Fig. 100, ?) are visible. Turning the specimen 

 over, introduce a small tube into the crescent-shaped 

 opening at the base of the third maxilliped, and blow air 

 through the tube into the opening. Turn the specimen 

 over again, and notice that the air has passed into the 

 branchial chamber, between the gills (I) and the roof (k). 



