SPH^EROMA. 403 



outer margin is affixed a triarticulated appendage.* The 

 inner maxillae consist of two nearly equal curved blades, 

 the inner of which is ciliated at the tip, and the outer 

 armed with strong spines. The outer maxillae are ter- 

 minated by three oval, very delicate plates, strongly 

 ciliated. The foot-jaws are large and strong, and close 

 the mouth ; they are composed of a strong, basal joint, 

 followed by a small joint, and are furnished with a large 

 triangular inner lobe, and terminated by four strong 

 joints of nearly equal length, but gradually diminishing 

 in thickness, and strongly ciliated. In some of the 

 species these four joints are internally produced into 

 a large lobe; the lower lip is rounded at the sides 

 and very deeply notched in the middle of the fore- 

 margin. 



The first segment of the body is larger than the fol- 

 lowing, and strongly produced backwards at its posterior 

 lateral angles ; the six following segments are marked at 

 the sides with an impressed oblique line indicating the 

 coxae or epimeral base of the legs ; the seventh segment 

 of the body is very short, and does not extend outwardly 

 so far as the first segment of the tail (pleon), which is 

 marked on each side with two transverse striae, which do 

 not unite in the middle of the back, but which represent 

 three segments coalesced together. The terminal joint is 

 large, and marked at its base with a rather deep transverse 

 channel. The legs are of nearly equal size ; they are 

 terminated by a bifid finger. The tail-plates (pleopoda) 

 consist of six pairs, five folding obliquely upon each 

 other, and received in a deep excavation on the underside 

 of the tail, of which the two last are furnished with bran- 



* Savigny (Egypte Crust., pi. 12, f. 1 i,) represents the middle joint as 

 divided into two, probably arising from the appendage having been twisted 

 in this part in the specimen dissected by him. 



D D 2 



