328 REV. T. R. R. STEBBIXG ON CRUSTACKA 



MALArOSTRACA. 



BRACHYURA. 



Tribe OYOLOMETOPA. 



Family Atelecyclid.e. 



Genns Peltarion Jacquinot. 



The systematic position of this genus and its nomenclature 

 have been already discussed in Proc. Zool. Soc. for 1900, pp. 518- 

 519, where also bibliographical details are supplied for the 

 following species. 



Peltarion spinosulus (White) juv. (PI. I.) 



Writing as to his collecting of Crustacea between I^ovember 

 1901 and March 1902 Mr. Vallentin says : — " I have dredged one 

 specimen of this species in Stanley Harbour in 3 fms. in the black 

 mud. It is common in certain protected bays fringing the ocean, 

 being easily procured during low-water spring tides. Its presence 

 can at once be detected by a slight blister in the sand. About 

 an inch deep in the sand under one of these mounds a crab can 

 always be secured. Gulls, Laras dominicanus, are splendid 

 fellows at finding those crabs. With one dig with their bill and 

 a twist they turn them out from their hiding places, and directly 

 tear them in pieces and devour them." 



Though the adult form of the species has long been well known, 

 I have not been able to find any description of the juvenile 

 stages, one of which seems to me to be represented by the minute 

 specimen which I have figured. 



The carapace measures about 3 mm. in length by 2 mm. in 

 breadth, while the adult may have a breadth of 50 mm. and a 

 length somewhat greater. The eyes of the small specimen are in 

 the Megalopa stage, and the five spinulose teeth on each side of 

 the carapace to the rear of the eyes and the spinulose eminences 

 along its medio-doi'sal line must undergo considerable modifi- 

 cation in the later development. On the other hand, the micro- 

 scopically denticulate rostrum and many other details are strongly 

 in favour of the proposed identification. Many points of agree- 

 ment may be observed by comparing the account wdiich Miei-s 

 gives of the genus (' Challenger ' Eeports, vol. xvii. p. 210, 1886) 

 with various details here figured. Attention may be called to 

 the third maxillipeds ; to the chelipeds (prp. 1) with the "fingers 

 robust, scarcely as long as the palm, and rather obscurely dentated 

 on the inner margins, distally acute ; the dactylus spiniiliferous 

 on the superior margin," as desci'ibed b}'^ Miers for the adult 

 male, and here only difiering by the greater length of the fingers 

 in relation to the palm, the other pera^opods also agreeing with 

 Miers's description, " dactyli styliform, slender, and much longer 

 than the penultimate joints." 



