80 



Orbits wide, their inner gap also wide ; external orbital tooth dis- 

 tinct, with at most only a trace of a gap between it and the lower orbital 

 margin. 



Antero-lateral margins of carapace Avell defined, sharpish, but hardly 

 crest-like, rather irregularly crenate, arched ; lateral epibranchial tooth well 

 formed, sharp. 



The epigastric and post-orbital crests form one bold much-undermined 

 ridge sweeping on either side, with a slight anterior concavity, from the 

 mesogastric fm-row to the lateral epibranchial tooth, but separated from that 

 tooth by the deep cervical groove ; the epigastric portion of each crest is 

 distinguished by a double or eroded edge. 



In the abdomen of the adult male the length of the 6th segment is equal 

 to its greatest breadth, the segment being squarish with the sides slightly 

 concave ; the length of the 7th segment exceeds its greatest breadth. 



Mandibular palp as in the type of the genus P. tridentata, Edw., the 

 1st and 2nd joints being fused together, and the terminal joint behig bilobed 

 from the base, the broad anterior lobe overhanging the ventral surface of the 

 mandible, and the falciform posterior lobe lying behind the incisor process 

 of the mandible. 



In the external maxillipeds the exopodite is much longer than the ischium 

 and carries the usual strong, plumose flagellum ; the ischium is longitudinally 

 grooved, and the merus is broader than long and has an oblique anterior 

 border. 



Tiie chelipeds are not very unequal in the female, but are considerably 

 unequal in the adult male ; in the merus the edges are crenulate and the outer 

 surface is transversely rugose ; in the carpus the upper and outer surfaces are 

 rugulose, and the inner angle forms a strong coarse spine; the palm and 

 fingers are pitted, the pits especially on the fingers having a linear arrangement, 

 and there are some squamiform tubercles on the upper surface of the palm ; 

 the tips of the fingers are hooked, and the fixed finger is much In-oader than 

 the dactylus. In the smaller cheliped the fingers are a good deal longer than 

 the palm, do not gape much when closed, and have fairly even teeth, one tooth 

 in the fixed finger being a little enlarged. In the larger cheliped the fingers 

 are as long as or very slightly longer than the palm, both of them have near 

 the base one tooth greatly enlarged, and the dactylus is considerably arched, 

 so that the fingers gape a good deal when the tips are apposed, this being 

 most marked in old males. 



The legs are very strong but are shorter than the chelipeds ; the longer 

 propodites are about twice as long as broad, and are not much shorter than 

 their dactyli in old males. 



This species attains a large size ; in the largest male the carapace is 

 3 inches long and 4 inches broad, and the hand (fingers included) of the 



