581 



are attached 3 slender bristles. Colour "somewhat varying, now more or less 

 dark reddish brown, now greenish, bnt generally exhibiting along the back a 

 series of light patches, one in each segment. Length of aduit female reach- 

 ing 18 mm, of male 20 mm. 



Remarks. - There cannot. I think, be any doubt, that the A. poflo- 

 ceroides of Rathke is the same species as that described many years pre- 

 viously by Montagu as Cancer (gammarus) rubricatus, and subsequently 

 recorded by British authors as Ampliitlioe nibricata. Kreyer described the same 

 species under another name, viz., A. albomaculata, and the A. littorina of Sp. 

 Bate is nothing less than an adult male of this species. The colour is rather 

 variable, according to the locality, and although I have never met with 

 specimens of that brillant crimson, described by British authors, it is not 

 unusual to find it of a deep reddish brown colour. Most generally however it 

 exhibits a lighter, more or less greenish hue, the body being mottled all over 

 with very small dark pigmentary spots. 



Occurrence. The species is very frequently found along the whole 



coast of Norway, from the Christianiafjord to Vadso, in comparatively shallow 

 water, among algse. According to Sp. Bate, it constructs itself a kind of 

 nest, composed of different foreign matters spun together by fine fibres. 



Distribution. British Isles (Sp. Bate), Bohuslan (Bruzelius), Kattgat 

 (Meinert), Heligoland (Meinert), coast of France (Chevreux), Azores (Barrois). 



G-en. 2. Pleonexes, Sp. Bate, 1857. 



Syn. : Amphithoe, Sp. Bate (part). 

 Sunamphithoe, Sp. Bate (part). 



Body less slender than in the preceding genus, otherwise of a very 

 similar appearance. Coxal plates of middle size, 5th pair with the anterior 

 lobe rounded at the tip. Eyes small. Antennae comparatively strongly built, 

 with the articulations of the flagella rather thick and very sharply defined, 

 the superior ones shorter than the inferior, and without any accessory appen- 

 dage. Mandibular palps very narrow, with the terminal joint linear, and 

 setiferous at the tip only. Posterior lip with the lateral lobes not hi lid at 

 the tip. Palp of 1st pair of maxillae having the terminal joint long and 

 narrow. Oral parts otherwise resembling those in Ampliitlw< : . Grnathopoda 

 comparatively stronger than in that genus, and rather unequal, the posterior 



77 Crustacea. 



