gg4 CRUSTACEA. 



articulated with the dorsal margin remote from the apex, the lower 

 part of outer surface of the hand not (?) minute scabrous, but the 

 hand having a more perfect form, and furnished with a stouter finger 

 articulated with the proper apex of the hand. Moreover, the upper 

 side of the fifth and fourth joints of the ten posterior legs is very often 

 naked, the setae or spinules being confined to the opposite or lower 

 side. 



The species differ from the Amphithoe group, in the absence of a 

 mandibular palpus ; in the Orchestia-like posterior stylets fitting them 

 well for saltatory habits ; in the small and slender one-jointed palpus 

 of the inner maxillae. They approximate most . nearly to the Iphi- 

 mediae; but these have the posterior stylets much longer and two- 

 branched instead of simple, besides having other characteristics of the 

 Gammarus tribe. Amphithoe Marionis (Edwards) is described as 

 having no mandibular palpus unlike other species ; but it is far re- 

 moved from Allorchestes in its long two-branched posterior stylets, as 

 well as in other particulars. 



The species among the following which have the carpus of the 

 second pair of legs in males produced downward in a process between 

 the hand and the third joint, are the Qaimardii, anstralis, and the 

 novi-zealandice, species from either New Holland or New Zealand. In 

 females this appears to be common, and the specimens obtained of 

 A. humilis and A. brevicornis are supposed to be females. 



1. Antennarum "Idarum basis Jiagello valde long lor. Antenna l??ice basi Zdarum 



breviores. 



Allorchestes Gaimardii? (Edw.), D. 



Corpus valde compressum, epimeris permagnis. Antennce superiores basi 

 inferiorum breviores, flagello li-articulato, fere duplo longiore quara 

 basis. Antennce inferiores dimidio corporis paulo breviores, crassius- 

 culm, siihpediforines, basi pradongo, Jiagello fere quadruplo breviore 

 quam basis, articulis basis tribus idtimis subo3quis, flagello 8-10-arti- 

 culato. Pedes Imi parvuli, manu vix oblongd, apice oblique truncatd 

 et paulo excavatd, basi parce angustiore, digito brevi. Pedes 2di 

 validi, manu magna subovatd, palmd rectiusculd, fere nudd, digito 

 longo, carpo infra tenuiter prodacto inter manum et articulum Stium. 

 Pedes 5ti §ti Imi sensim increscentes, setts sparsis minutissimis diametro 

 articidi hti 4p>lo brevioribus. 



