38 



A. vulgaris in the shape of the genital area excepting that the couple of protuberances between 

 the basal parts of the coxre of third pair of legs are quite absent; in this feature it agrees 

 with A. Sibogce^ but differs from this form in having no vestige of an elevated area between 

 the coxEe and the transverse furrow. 



Remarks. — It may be seen that the two specimens described exhibit characters found 

 in A. vulgaris and others found in A. Sidogo', while in the spines on the lower antennular 

 flagellum, in the armature on the capitulum of the petasma and in the female genital area they 

 differ from the two species named. Havingr only i male and i adult female I do not venture 

 to establish a new species, though it is impossible to refer the specimens either to A. vulgaris 

 or to A. Sibogcc\ one is nearly tempted to suppose that the specimens may be bastards between 

 the two species. Future students who possess a good material of this dubious form and allied 

 species, may decide the question. 



2. Acetcs Sibogce n. sp. PI. Ill, figs. A,a — \h. 



Stat. 47. March 8 — 12. Bay of Bima, near south fort. 55 m. Mud with patches of fine coral 



sand. 16 specimens of both sexes. 

 Stat. 323. Febr. 24 — 25. Sangkapura-roads, Bawean-island. 12 m. Mud. 10 adult males, 16 



adult females, and 22 immature specimens. 



Male. — Eyes (fig. i\a^ smaller than in A. vulgaris, as the transverse diameter of the 

 cornea is slightly more than half as long as the distal joint of the stalks with eye. Antennulae 

 with second joint conspicuously longer and thicker than in the female, third joint slender and 

 very elongated, not fully two and a half times as long as the inner margin of second joint. 

 Thickened part of upper flagellum a little shorter than the inner margin of second joint. Lower 

 flagellum at most a little longer than the inner margin of second peduncular joint, with 13 

 joints (fig. 4^); the shaft of the clasping organ is 3-jointed, the jointed main "branch" with only 

 10 joints, consequently considerably shorter than in A. vulgaris^ while its proximal half is rather 

 curved and armed below with spines nearly as in that species; a single long, robust, moderately 

 curved spine originates beneath the base of fourth joint of flagellum and reaches nearly to the 

 spines on fifth joint of the main "branch". Antennal squama reaches to the end ot second 

 antennular joint. Coxae of third pair of legs (fig. 4^/) without any vestige of a tooth at the 

 distal inner angle. Genital coxae (fig. \d) as long as broad, with the terminal corner produced 

 as a very short, subacute process. Exopod of uropods (fig. 4^) nearly four and a half times 

 as long as broad; on the outer margin the ciliated part occupies slightly more than two-fifths 

 of the whole length. 



The petasma (figs. 4/ — 4//) is related to that in A. vulgaris, but shows some differences. 

 The inner margin with hooks of pars astringens is considerably shorter than in A. vzilgaris, 

 while the differences observed in the pars externa and the proximal half of pars media are 

 slight. The processus ventralis [pv.) is not as long as in A. vulgaris, and its outer margin is 

 much more sinuate. The capitulum (r.) is rather different; it is twice as long as processus 

 ventralis and more than three times as long as thick ; a little more than its distal third is a 

 slender process tapering to the narrow, obtuse end; near the outer margin towards the processus 



