REPORT ON THE CRUSTACEA MACRURA. 263 



longitudinally traversing the propodos, which does not exist in Penaeus velutinus. But 

 the great distinction from other species exists in the form of the ventral surface of the 

 posterior somites of the pereion in the female, and in that of the petasma attached to the 

 first pah- of pleopoda in the male. In the female, originating within the posterior margin 

 of the ultimate somite of the pereion, are two flat plates, separated from each other by a 

 median furrow ; they proceed forwards as far as the anterior margin of the penultimate 

 somite, and anteriorly are widened outwards. The third pair of pereiopoda carries the 

 oviducts, each of which opens by a small foramen at the extremity of an elongated 

 tubercle, that is directed oblicraely backwards nearly to the anterior margin of the 

 thelycum ; and there exist no long and slender teeth between the coxae of the second pair 

 as in Penaeus velutinus. The first pair of pleopoda in the female does not differ 

 materially from that in Penaeus velutinus, but in the male the petasma differs in having 

 the extremity of the left side, which is the longer, and which projects forwards in Penaeus 

 velutinus, coded up and doubled inwards in this species (fig. 3"). Consecraently the 

 following distinctions wdl be found to be means of ready diagnosis in determining 

 Penaeus philippinensis from Penasus velutinus, namely, the length and horizontal position 

 of the rostrum ; the furry character of the synaphipod of the mandibles ; the arrange- 

 ment of the petasma attached to the first pair of pleopoda in the males; the absence 

 of the long, spine-like, ventral teeth between the second pair of pereiopoda in the 

 females ; the reduced depth of the carina on the dorsal surface of the last two somites of 

 the pleon, and the shortness of the telson, which is armed with three articulated spines 

 and a small fixed tooth on each side behind and above the posterior spine. 



The above description is drawn from specimens which were taken amongst the 

 Celebes Islands, and it applies to all the adult forms. 



In the younger males, judging from a sobtary half-grown specimen, the fobaceous 

 ramus of the first pair of pleopoda is neither broad nor well developed, and is probably 

 immature. The extremity of the vas deferens projects from the coxa of the posterior 

 pair of pereiopoda, and when elongated falls into a groove on the posterior surface of the 

 petasma, and is probably in this way directed and held in position during coition. 



From the branchial chamber of one or two male specimens I took a large species 

 of Bopyrus. 



Penaeus jissurus, n. sp. (PI. XXXVI. fig. 1). 



Eostrum reaching but little beyond the extremity of the first joint of the first 

 pair of antennae ; dorsal margin furnished with six smaU teeth and one remotely 

 posterior upon the gastric region, from which a small carina passes to the posterior 

 margin of the carapace ; inferior margin ciliated. Pleon compressed and carinated 

 from the third somite. The posterior margin of the fourth, fifth, and sixth somites 



