548 



nearly transversely truncated at the tip. Anterior gnathopoda in male 

 extremely large and powerful, with the outer part densely setous on both 

 edges, carpus rather thick, with the upper face boldly curved and clothed 

 all over with numerous very slender and diverging bristles springing from 

 small tubercles, propodos oval in form, and about same size as the carpus, 

 likewise having the upper face densely clothed with diverging bristles, palm 

 comparatively short, and divided into two strong dentiform projections, the 

 lower of which is the larger, and having at its base a small spinule, 

 dactylus of moderate size, and minutely denticulated inside. Posterior 

 gnathopoda in male of a structure similar to that in the female, though 

 comparatively larger, and having both the carpus and propodos densely 

 clothed with bristles, especially along the upper face. Last pair of pereiopoda 

 equalling about half the length of the body, basal joint oblong oval in form. 

 Last pair of uropoda with the rami subequal, and about the length of the 

 basal part. Telson rounded oval in form, with 3 spines on either side of the 

 somewhat angular tip. Body whitish, mottled with small specks of a dark 

 brown pigment, forming more or less distinct, narrow bands across the seg- 

 ments and coxal plates. Length of adult female 5 mm, of male 6 mm. 



Remarks. This form was at first described by Sp. Bate as Lembos 

 Websteri, and was subsequently referred by him to the genus Microdeutopus. 

 It is, however, a true Autonoe in the restriction of the genus adopted by 

 Boeck. I have myself formerly erroneously identified it with Gammarus 

 longipes of Lilljeborg. From the latter it is easily distinguishable by its 

 much more robust form of body, by the more fully developed accessory append- 

 age of the superior antennae, by the structure of the gnathopoda in the two 

 sexes, and finally, by the rather different colour of the body. 



Occurrence. I have met with this species in several localities ot 

 the south and west coasts of Norway, though nowhere in any abund- 

 ance. It ig generally found in comparatively shallow water, together with 

 Microdeutopus danmoniensis and gryllotalpa. 



Distribution. - British Isles (Sp. Bate), coast of France (Chevreux). 



