373 



with the rostrum rather large and evenly curved downwards, lateral corners 

 small. The 3 anterior pairs of coxal plates rather narrow, and tapering to 

 a point; 4th pair considerably larger and securiform in shape, outer part 

 triangularly pointed; the 2 succeeding pairs of moderate size, with the posterior 

 lobe deeper than the anterior. Eyes comparatively small. Superior antennae 

 with the peduncle rather elongated. Anterior lip narrowly prolonged and 

 minutely incised at the tip; posterior lip with the lobes narrowly produced. 

 Mandibles rather elongated, cutting part narrowly projected, and having on 

 both mandibles a very narrow accessory lamella, molar expansion obsolete, 

 palp slender. First pair of maxillse with the masticatory lobe very obliquely 

 truncated at the tip, and armed with short denticles, basal lobe triangularly 

 pointed, and provided on the inner edge with numerous short setse, palp com- 

 paratively small. Second pair of maxillae with the outer lobe much larger 

 than the inner, and obliquely truncated at the tip. Maxillipeds having the 

 basal part broad and laminar, basal lobes nearly of same size as the masti- 

 catory ones, palp comparatively small, with the dactylus very minute. 

 Anterior gnathopoda extremely slender and attenuated, monodactylous; 

 posterior gnathopoda shorter and stouter than the anterior, and not sub- 

 cheliform. Pereiopoda comparatively strong, basal joint of the 3 posterior 

 pairs moderately expanded, and more or less produced at the infero-posteal 

 corner. Last pair of uropoda with the inner ramus longer than the outer. 

 Telson oblong oval in form, with the apical incision rather narrow. 



Eemarks. - - This genus was at first established, in the year 1833 by 

 Owen, to include the arctic species A. cristata, described in the sequel. As, 

 however, the generic name he proposed, Acantlionotus, was already applied to a 

 genus of fishes, it was subsequently changed by Mr. White to Vertumnus. 

 Neither can this name, however, be admitted, since it has been given, at an 

 earlier date, by Otto, to a genus of Turbellarise. Under these circumstances, 

 the generic name, Acanthonotosoma, proposed by Boeck in his great work, must 

 be adopted, although it is somewhat uncomfortable from its length, being com- 

 posed of no less than 7 syllables. The species belonging to this genus exhibit, 

 in their external appearance, a considerable resemblance to those of the genus 

 Ephneria, but may be easily distinguished by the greatly projecting buccal 

 area, and by the peculiar structure of the gnathopoda. The genus comprises 

 as yet but 3 species, 2 of which will be described in the sequel, the third 

 being the Acanthonotus inflates of Kroyer, which has not yet been recorded 

 from the coast of Norway. 



48 Crustacea. 



