1922.] 



W. M. Tattersall : Indian Mysidacea. 



455 



margin of the inner uropods have smaller spines in between them, 

 so that the spines as a whole are arranged in series of 3-5. 

 Hansen gives no particulars on this point in his text but his figure 

 does not show the intermediate spines. In other respects the 

 specimens agree with S. affinis and provisionally I record them 

 under that name. 



Distribution. — Known only from the waters of the East 

 Indian Archipelago. 



Siriella dubia Hansen. 



Text-figs. $a, b. 



Siriella dubia, Hansen, [910, p. 44, pi. v, figs. ±a-e. 



Locality. — Port Blair, Andaman Islands, Station 19. Eight 

 specimens: largest female, 8 mm., largest male, 7*5 mm. 



Remarks. — These specimens differ in one important feature 

 from the description and figures of Hansen. There are three 

 small spines, equal in size to 

 one another, between the inner 

 pair of large terminal spines 

 at the apex of the telson, in 

 addition to the usual pair of 

 plumose setae. Hansen parti- 

 cularly emphasizes the absence 

 of these spines in his single 

 specimen but the present speci- 

 mens are so very closely in 

 agreement with Hansen's des- 

 cription and figures that I can 

 only suppose that the spines 

 were overlooked or broken off 

 in his type. 



All the specimens have four 

 spines on the outer margin of 

 the proximal joint of the outer 

 uropod in the positions indica- 

 ted in Hansen's figure 4^, with the addition of an extra spine bet- 

 ween the two proximal ones of his figure, as mentioned in his text. 

 The serrations on the proximal margin of th? outer uropod are 

 in reality the bases of plumose setae, which have become detached. 

 Several of my specimens still retain some of these plumose setae, 

 so evidently the serrations do not indicate the base of broken 

 spines. In the smallest specimen, 4*5 mm. long, the outer and 

 inner uropods are equal in size ; there is a progressive difference in 

 size between the two uropods, with an increase in the total length 

 of the animal 



The last joint of the antennular peduncle in the male is longer 

 and stouter than in the female and furnished with the usual brush 

 of setae. In the adult male, therefore, the antennal scale is 

 shorter than the antennular peduncle, whereas in the female it 



Text-fig. 5. — Siriella dubia, 

 Hansen. 



a, fourth pleopod of the male, X 

 b, distal joints of the exopod 

 further enlarged, X !oo. 



33 



