REPORT ON THE CRUSTACEA MACRURA. 265 



the apex of which the frontal margin continues in advance until it again forms a hollow 

 on the inner side of the antenna! tooth, in which depression a fissure in the integument 

 originates and continues in an almost direct line to near the posterior margin, where 

 it abruptly terminates. Another tooth stands on the hepatic region, and another small 

 one projects from the fron to -lateral angle of the carapace. 



There is no carina on the dorsal surface of the first and second somites of the 

 pleon, but one commences on the third, increases posteriorly, and terminates in a 

 tooth at the extremity of the sixth somite. The telson is nearly as long as the inner 

 branch of the rhipidura, and is dorsally grooved in front in a longitudinal direction, 

 longitudinal and flattened posteriorly, where the sides project into a strong tooth, and 

 the margins are frino-ed with long cilia. 



o o o 



The ophthalmopod is Inarticulate ; the first joint carries on the inner distal extremity 

 a broad, flattened, anteriorly-directed tooth ; the second supports the ophthalmus, which is 

 somewhat pear-shaped, being narrow at the peduncle, flattened on the inner side, rounded 

 externally and oblong longitudinally, and reaching nearly to the extremity of the 

 rostrum. 



The first pair of antennae reaches to about twice the length of the rostrum and 

 supports two slender, unequal flagella, the inner being shorter than the peduncle and 

 the outer half its length. The prosartema is not so long as the ophthalmopod and is 

 fringed with long cilia ; the stylocerite is nearly as long. 



The second pair of antennae is nearly twice as long as the animal, its scaphocerite 

 reaches beyond the peduncle of the first pair, and its rigid outer margin is continued to 

 a small tooth that projects near the distal extremity of the scale. 



The first pair of pereiopoda carries a sharp, strong tooth on the basisal and one on 

 the ischial joint, but there is none on the second and third pairs. 



The fourth and fifth pairs are more slender than the preceding chelate limbs, and 

 terminate in somewhat long and rather compressed dactyli. The fifth does not 

 possess the excavation in the frontal margin of the ischium which is seen in the near 

 allies Penasus incisipes and Penseus affinis. 



The specimens that were trawled at Station 209 differ from those from Station 204, 

 although in the same immediate region among the Philippine Islands, in having the 

 rostrum longer, being quite half the length of the carapace, and in having the flagella 

 of the antennas somewhat longer. At first I thought that the two were distinct 

 varieties, but I believe they can only be considered rather as strongly developed specimens 

 of the same species. Among the former are several specimens of the male in which the 

 first pair of pleopoda carries a petasma that is longitudinally folded on itself, and the 

 apex or distal extremity is doubled in complex folds, forming two heads too complicated 

 to describe, and the second pair carries a large button-shaped process ; all the others are 

 of only generic value. 



(ZOOL. CHALL. EXP.— PAET LII. — 188G.) Fff 34 



