_>:;<; CEYLON PEARL OYSTER REPORT. 



telson, which is unusually diaphanous and easily overlooked ; while he lias mistaken 

 the 1st uropods for the 2nd owing to the former crossing the latter, as is common in 

 a mounted specimen. Asa matter of fact, the uropods are quite normal. The line of 

 demarcation between the 2nd and 3rd urosome segments is also very difficult to see; 

 it is correctly shown by Stebbing (loc. cit., Plate 107) at the base of what was 

 believed by Giles to be the telson. The posterior angle of the 3rd pleon segment is 

 a sharp right angle as in II. dysschistus, and not rounded as drawn by Giles. 



There is no doubt that our specimens are II. dysschistus, Steb., and, considering 

 the localities and the deceptive nature of the characters in which Dr. Giles lias 

 erred, that they are also H. bengalensis (Giles). 



The gnathopods agree well with the figures of II. dysschistus in Bovallius (loc. 

 cit., Plate XI, figs. 1, 2). 



This species presents a curious case of male dimorphism. The lower antennae of the 

 smallest males (2 '2 5 millims.) have the very long and slender flagella generally 

 considered characteristic of sexual maturity, while other males, with the antennae 

 imperfectly developed, measure 3 - 25 millims. Perhaps, as in the case of Bathyporcui 

 pilosa, Lind., mentioned by Bonnier (' Travail du Lab. de Zoologie de Wimereux'), 

 the males become sexually mature before they are full grown, and lose their nuptial 

 appendages after copulation. 



Several specimens from various localities at Ceylon. 



Hyperia crucipes, Bovallius. 



In addition to the distinctive characters given by Bovallius may be mentioned 

 the great relative width of the 4th and the ciliate margin of the 5th joint in the 1st 

 and 2nd peroeopods. 



Two, young, Station LXVI. Length 2 "5 millims. 



Hyperoche, Bovallius, 1887. 



Hyperoche cryptodactylus, Stebbing, ' " Chall." Amph.,' p. 1399, Plate L70. 



One male, length 4 millims., Galle harbour. 



The " Challenger" specimen was taken near the Cape of Good Hope. 



Phrosina, Eisso, 1822. 

 Phrosina sp. 



One, young no locality. Length 2 '5 millims. 

 Too young for identification. 



Parascelus, Claus, 1879. 



Parascelus parvus, Claus Plate L, fig. 1. 



One, male, length 3 '5 millims. 



The first (upper) antennae have the 1st joint of the flagellum very wide and as long 

 as the next two (fig. 1. ant. 1 ). 



