545 



the northern form described below, the Rev. Mr. Stebbing has added 2 new 

 species from the Challenger Expedition. The genus thus at present 

 comprises 4 species. 



4. Aora gracilis, Sp, Bate. 



(PI. 191). 

 Lonchomeres gracilis, Sp. Bate, Brit. Assoc. Report 1855, p. 68. 



Syn. : Lalaria gracilis, Sp. Bate. 

 Autonoe punctata, Bruzelius. 



Body rather slender, nearly cylindric, with broadly rounded back. 

 Cephalon not quite as long as the first 2 segments of mesosome combined, 

 lateral corners obliquely rounded, postantennal ones well defined. Anterior 

 pairs of coxal plates somewhat deeper than the corresponding segments, 1st 

 pair in female scarcely widening distally, in male much larger, and obliquely 

 expanded, 4th pair in female obliquely truncated at the tip, 5th pair with 

 the anterior lobe somewhat deeper than the posterior, and evenly rounded. 

 Last pair of epimeral plates of metasome nearly rectangular. Eyes small, 

 rounded oval, pigment black with a whitish coating. Superior antennae very 

 slender, equalling 2 /3 of the length of the body, 2nd joint of the peduncle the 

 longest, flagellum twice the length of the peduncle, and composed of 20 30 

 articulations, accessory appendage well developed, fully twice as long as the 

 last peduncular joint, and composed of 5 articulations, the last of which is 

 very small. Inferior antennae scarcely more than half as long as the 

 superior, the last 2 joints of the peduncle about equal-sized, flagellum scarcely 

 longer than the last peduncular joint. Anterior gnathopoda in female with 

 the propodos nearly twice as long as the carpus, and slightly expanded 

 distally, palm oblique and not distinctly defined. Posterior gnathopoda some- 

 what more feeble in structure, with the propodos but little longer than the 

 carpus, and less expanded distally. Anterior gnathopoda in male very large 

 and elongated, attaining, when fully extended, half the length of the body, 

 meral projection mucroniform, and extending beyond the carpus, the latter 

 of nearly equal breadth throughout, propodos a little shorter than the carpus 

 and narrow oblong in form, without any distinct palm, dactylus very large 

 and compressed, impinging, when closed, against the lower face of the meral 

 process. Posterior gnathopoda of same structure as in the female, but some- 

 what larger. The 3 posterior pairs of pereiopoda rapidly increasing in length, 

 last pair very much elongated, considerably exceeding half the length of the body, 



72 Crustacea. 



