549 



6. Autonoe longipes, (Lilljeborg). 



(PI. 195, fig. 1.) 

 Gammarus longipes, Lilljeborg. 0fvers. af Kgl. Svenska Vet. Akad. Forhandl. 1852, p. 10. 



Syn : Microdeutopus longipes, Sp. Bate. 

 Autonoe plumosa, Boeck. 



Body considerably more slender than in the preceding species, and 

 nearly cylindric in form, otherwise of a very similar appearance. First 

 pair of coxal plates in male not nearly so much produced in front as in the 

 male of A. Websteri. Eyes small, rounded, pigment black. Superior antennae 

 about equalling in length 2 /s of the body, 2nd joint of the peduncle much 

 longer than the 1st, flagellum somewhat longer than the- peduncle, and com- 

 posed of about 18 articulations, accessory appendage scarcely longer than 

 the last peduncular joint, and 3 articulate, inferior antennae, of the usual 

 structure. Anterior gnathopoda in female less strongly built than in the 

 preceding species, propodos somewhat longer than the carpus, and gradually 

 widening distally, palm rather oblique, and denned below by an obtuse angle 

 carrying a slender spine. Posterior gnathopoda scarcely shorter than the 

 anterior, but somewhat more slender, propodos about the length of the 

 carpus, and very little expanded distally, palm nearly transverse. Anterior 

 gnathopoda in male rather large, with the basal joint much expanded, and 

 clothed at the infero-posteal corner by a dense brush of long and slender bristles 

 curving anteriorly, carpus setous only in the outer part of its upper face, 

 propodos exceeding the carpus in length, and oblong oval in form, with the 

 upper face setous throughout, palm somewhat oblique, and, as in the preceding 

 species, divided into 2 dentiform projections, the inferior of which is the 

 larger. Posterior gnathopoda in male much larger than in female, and nearly 

 as long as the anterior, though not nearly so strongly built, carpus and 

 propodos densely clothed with slender bristles along their upper face. Last 

 pair of pereiopoda very slender and elongated, exceeding half the length of 

 the body. Last pair of uropoda with the rami nearly twice as long as the 

 basal part, and subequal. Telson rounded oval, outer part somewhat tapering. 

 Body whitish, with light reddish bands across the segments, but without 

 any pigmentary specks. Length of adult male nearly 12 mm. 



Remarks. - - There cannot be any doubt that this is the form originally 

 recorded by Prof. Lilljeborg as Gammarus longipes, and subsequently described 

 and figured by Bruzelius under the above name. The Autonoe plumosa of 



78 Crustacea. 



