48 



Remarks. — This small species is easily distinguished from H. p-iilckra by the uropods. 

 The Copenhagen Museum possesses 6 specimens taken in the Bay of Bengal: lat. 6°22'N., 

 long. 95°54'E.; 5 of these specimens are females, the sixth specimen is a very small male, 

 4.9 mm. long, in which the telson is nearly as in the female, but perhaps it is not quite full-grown. 



Subfamily III. Rhopal ophth al m in se n. 



The characters of the subfamily are given in the synopsis on p. 11 — 12. Only one 

 eenus is known. 



& 



Rhopalophthalmus Illig. 



Description. — General aspect about as in Siriclla. Carapace very short. Eye-stalks 

 somewhat long or very long. Antennular peduncles in the female moderately slender, in the 

 male somewhat thicker, especially their the distal part; first joint nearly as long as the sum 

 of the two distal joints, and the major part of its outer lateral margin furnished with plumose 

 setse directed upwards and inwards in a most aberrant way (PI. VI, fig. 3«); third joint in the 

 male with the lobe bearing the sensory setse not distinguishable; outer flagellum in the male 

 thickened and much expanded towards the base. Antennal squama moderately long, somewhat 

 narrow, with the outer margin naked and terminating in a tooth. Labrum transverse, without 

 process in front. Mandibles with the movable lacinia thick; the left mandible (fig. 3(:) without 

 setae, the right (fig. 3^') with a single, thick seta behind that lacinia; molar process of the left 

 mandible thick, much produced, with teeth on the end, that of the right mandible thick, slightly 

 produced, with a few, blunt tubercles on the terminal surface; the palp moderately short, very 

 feebly expanded (fig. 3^). Maxillae (fig. ^e) with the lobe from third joint deeply cleft, the palp 

 rather small, the exopod small. Ma.xillipeds (fig. 3/) with second joint large and produced into 

 a conspicuous lobe; the other joints slender; a claw not distinguishable. Gnathopods (fig. 3^^) 

 as in Siriella, without lobes from any joint. Thoracic legs (fig. 3//) subsimilar, slender; sixth 

 joint subdivided by some articulations; seventh joint and claw rudimentary or wanting. Pleopods 

 in the female unusually long: those of fifth segment only a little shorter than the segment itself 

 Pleopods in the male well developed; first pair (fig. 3 z j with the exopod multiarticulated, the 

 endopod much shorter, with the protuberance minute; second pair (fig. 3/') with the exopod 

 very elongated; the other pairs with both rami subequal ; a kind of lamellar pseudobranchiae are 

 found in the four posterior pairs, and these lamellae are — at least in the species known to me — 

 trilobate on second to fourth pairs with the lobes very unequal in size. Uropods (PI. VII, fig. i c) 

 very slender, each ramus divided by a well developed articulation beyond the middle, exopod 

 with the outer margin very finely serrate and — according to Illig — setose; otocyst well 

 developed. Telson Hnguiform, distally without incision. 



Remarks. — This genus was established by Illig in a preliminary note on the 

 "Valdivia" Mysidacea (Zool. Anz. B. XXX, 1906, p. 207). Illig does not mention the articulation 



