behind the middle of the distance between the posterior tooth and the hinder angle of the 

 carapace, the latter is crossed by the second transverse suture, which is nearly straight, but 

 somewhat produced in its median part. The length of the carapace (not including the rostrum) 

 is distinctly shorter than the breadth ; the hinder margin is longer than the distance between 

 the external orbital angles. 



There are scarcely fossae for the orbits ; the . eye-stalks are free, directed obliquely- 

 outward and forward, granular at upper surface, thick and rather long (^5 breadth of carapace); 

 the cornea is small, occupying the tip of the stalk and semilunar in shape, if viewed from 

 above. Laterally of the bases of the eye-peduncles is an incomplete transverse fossa, scarcely 

 extending tD external orbital angle, and incompletely closed ventrally by the inflated basal joint 

 of the antennule, the peduncle of the antenna and the infra-orbital spine, an arrangement that 

 is characteristic for the genus. 



The infra-orbital spine is prominent, straight, directed forward and finely crenulate at the 

 borders; it reaches beyond the basal joint of the antenna, which is quadrate, not inflated and 

 nearly as long as the third joint; the next joint is twice as long; the flagellum consists of 

 about 25 joints, each of which has two short hairs; the whole flagellum is half the length of 

 the carapace. The basal joint of the antennules is globular, inflated, granular (as in Ji. dcntata), 

 freely movable (fig. i a), with the antero-internal angle somewhat projecting and giving rise to 

 the two next joints, that are cylindrical and of about equal length (as long as the transverse 

 diameter of the basal joint); they are much stouter and longer than the peduncle-joints of the 

 antenna. Antennulae, antennae and infra-orbital spine arise all at the same level ^), on the inferior 

 border of the orbito-antennulary fossa; the eyes reach farther outward than the basal antennular 

 joint and may touch the infra-orbital spine "). 



The chelipeds are unequal in size, the right being the stouter, quite as in R. dcntata 

 and apparently also as in R. jiotopzis '") ; yet the difference between the chelipeds is especially 

 shown by the relative development of the palm and the fingers. The description given by 

 Mac Gilchrist is wholly applicable to my specimen: the right cheliped is thicker in all its joints, 

 and, though the hands are of equal length, the right hand has a higher and more inflated 

 palm, that is granular at outer surface, and as long as the fingers, whereas in the left hand 

 the palm is much weaker and lower, and shorter than the fingers. Both palms are serrated 

 along the upper border and the proximal half of the inferior border, and parallel to this latter 

 border a continuous row of small granules is continued to quite near the tip of the fixed finger 

 (fig. 1(5, i^). The fingers are high at the base, greatly compressed, not gaping and tapering 

 to the acute tip ; on the right side (fig. i d) the cutting margins of the fingers are provided 

 with 3 — 4 very large, interlocking, obtuse but sharp-edged teeth, but on the left there are 

 only a number of very small denticles on the fixed finger, the opposite margin of the movable 

 finger being unarmed. 



1) According to Alcock the antennae arise just below the infra-orljital spine, in X. iiolopus. 



2) Mac Gilchrist notes that in R. dentata the eye-stalks reach as far outward as the basal antennule-joint; my specimen on 

 the other hand agrees in this respect with what is found in R. notopus. 



3) In Doflein's specimen of R. chuni only the right cheliped was present. 



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