STALK-EYED CRUSTACEA 493 



I. Notostomus. 



Notostonms ... A. Milne Edwards, Spence Bate, 



Smith. 



The dorsum is elevated into a keel extending from the 

 rostrum, which is toothed above and below, to the telson. 

 From the apex of the rostrum, corresponding with its 

 infero-lateral margin, a second keel traverses the carapace 

 along the upper line of the branchial region to its posterior 

 margin. The dorsal surface of the carapace is arched, 

 especially over the frontal and gastric regions ; the 

 rostrum is horizontally straight. The eye - stalks are 

 widely separated at their base, and carry a large cornea at 

 their extremity. 



The peduncle of the internal antennas is shorter than 

 the rostrum ; the first joint is long and excavated above 

 to receive the eye, and carries a short, broad, and pointed 

 external spine ; the next two joints are short, and carry 

 one stout and one slender flagellum, the former gradually 

 tapering to a fine extremity. The external antennae have 

 the peduncle robust, which carries a broad basal scale that 

 is rounded at the extremity, and armed on the outer distal 

 margin with a strong tooth. The mandibles have a large 

 and broad cutting edge that is slightly serrate, and con- 

 tinuous with a small, smooth, lunate molar process, and 

 carry a stout three-jointed palp, of which the terminal 

 joint is short and spatuliform. 



The first pair of legs is shorter than the second. The 

 third and fourth pair are long, and have the sixth joint 

 more slender than the preceding joints ; the terminal joint 

 is long, styliform, and slightly curved. The fifth pair 

 resemble the two preceding, but terminates in a short. 



