MOUNT ROKAULA [.\ BRITISH GL'[A\A. 57 



CRUSTACEA. 



By Dr. J. G. de Max. 



(Plate 6.) 



PaLtEMON (MaCROBUACHIUM) QtiELCUI, .sj). II. 



Thirty-seven specimens, only five or six of uiiich are full-grown, were collected in the 

 Upper Mazaruni river at an altitude of 2500 feet, and one young specimen was captured 

 at an altitude of 3500 feet on the Mt. Pvorainia range. Amongst the lormer is ])ut one 

 ova-bearing female, the rest are both males and young females, the full-grown specimens 

 being all males. 



This pretty species, that I have the pleasure to name after Mr. .). J. Quelch, is 

 apparently closely allied to Fal. potluna, P. Miiller, from the Itajahy river. State 

 of Santa Catliarina, and to Fal. Iheringi, Ortm., from tlie State of Sao Paulo, both in 

 the south of Brazil ; but it is no doubt different, the second legs presenting characters 

 intermediate between those of the two quoted species. Palcemon Qmlchi is evidently 

 their representative in British Guiana. One full-grown specimen only is still provided 

 with both legs of the second ])air, in tlie others one of tliem is lost. The ova-bearing 

 female has also lost these legs, and in the numerous young individuals one leg of this 

 pair or even both are often wanting. 



Falasmon Quelchl belongs to the species of sum// size, the adult individuals mcasurino- 

 only 55 millim. from tip of rostrum to the extremity of the telson. Examined under a 

 rather strong lens the cephalothorax presents a tine and rare puuctation, on wliich one 

 observes a short pubescence, for the rest it appears smooth. The rostrum (PI. 6. figs, l-i), 

 vertically moderately deep, is rather short, reaching only the end of the antennulary 

 peduncles or even only the middle of their terminal joint, so that it does not extend to 

 the end of the antennal scales. The iipper margin, usually very slightly convex above 

 the eyes, gradually descends downwards and carries sereii, eiyht, or nine low, rather 

 equidistant teeth, the first two of which commonly stand ou the cephalothorax, l)ut 

 often only one tooth stands on it, the second being placed above the orbital maru:in. 

 The lower margin is usually armed with two teeth, often, liowever, witli one only. The 

 formulae for 34 specimens are the following : — 



o specimens ., ; 4 specimens j ; 9 specimens r, ; 



* . - ' . r [ . 



1 specimen !^. 



The hepatic spine is small and placed below and posterior to the somewhat larger 

 antennal one. The apex of the telson, as usual shorter than the lateral appendages and 

 the flattened upper surface of which bears the two ordinary pairs of small spinules, is 

 triangular with a quite short median spine ; the inner spinules are somewhat longer 

 than the median point and considerably longer than the outer ones. 



The free end of the antennal scales is obtusely angulated internallv and reaches a little 



