446 MR. J. R. HENDERSON— A CONTRIBUTION 



Genus ^Egeon, Risso. 

 268. ^Egeon orientalis, n. sp. (PI. XL. figs. 16, 17.) 



Gulf of Martaban, a female ( Oates). 



The rostrum is shorter than the eyes, and excavated dorsally, with the apex obtuse 

 and minutely bidentate ; a small tooth is placed on either side of the middle of the 

 rostrum. The carapace has a median and three lateral rows of teeth on each side, 

 running the entire length from end to end. The median row is composed of five equal 

 teeth, the first placed at a short distance from the rostrum. The submedian row is com- 

 posed of seven subequal teeth, the most anterior of which is placed in front of the first 

 of the median row. The lateral row is also composed of seven teeth, but they gradually 

 diminish in size on passing backwards, and the most anterior is placed on the same level 

 as the first tooth of the median row. The lateral marginal row is composed of seven 

 teeth, the first placed immediately behind the large antero-lateral spine of the carapace, 

 and well developed ; the second is smaller, and the rest are minute, becoming almost 

 imperceptible behind. A prominent spine occurs on the anterior margin of the carapace, 

 external to the eye, but it is only about half the size of the antero-lateral spine. 



The first legs are rather stout ; the second pair slender and chelate, scarcely reaching 

 the middle of the propodus of the first pair ; the third pair very slender, and slightly 

 longer than the first pair ; the last two pairs rather stout. The antennal scale is short 

 and broad, only slightly longer than the antennular peduncle, with a dense fringe of 

 long hairs on its inner margin. The terminal segment of the antennular peduncle 

 extends to the middle of the last joint of the antennal peduncle. The external maxilli- 

 pedes are slightly longer than the first legs. The abdominal segments have a series of 

 submedian and lateral dorsal keels ; on the first segment a submedian pair, and a lateral 

 pair on either side ; on the next three segments a single median keel, with a single 

 lateral one on either side ; and on the fifth and sixth segments a submedian pair, with a 

 single lateral keel on each side. The submedian keels on the third and fourth segments 

 are more pronounced than any of the others. The telson is acuminate, and faintly 

 channelled dorsally. 



The single specimen is 27'5 mm. long, measured between the apices of the rostrum 

 and telson. 



The Burmese species bears a general resemblance to A. cataphractus (Oliv.), from the 

 Mediterranean, but the latter has the teeth of the carapace both more prominent and 

 more numerous, while there is a concavity on each hepatic region, in addition to other 

 differences. There can be no doubt, however, that the two species are congeneric. 



Group Pen^idea. 

 Genus Pen^us, Fabricius. 



I have included all the species of Penceus referred to in this paper, provisionally at 

 least, in a single genus, though, so far as I know, only P. monodon and P. indicus belong 



