462 



urosome. Also, the peculiar inversion of the dactylus, which occurs in all 

 the forms on some of the posterior pairs of pereiopoda, is very characteristic, 

 as also the deeply-fissured telson, and the generally very complicated structure 

 of the branchial lamellae. Whether the genera Atyloules and Atylopsis of 

 Stebbing should be referred to this or the preceding family, seems to me 

 to be still somewhat doubtful. The family comprises 4 genera represented 

 in the fauna of Norway, one of which is now for the first time established. 



Gen. 1. ParatyluS, G. 0. Sars, n. 

 Syn. ; Atylus autorum (part). 



Body much compressed, and keeled dorsally, with the urosome always 

 produced at the end to a compressed dorsal projection, in front of which 

 there is a small notch. Cephalon rather deep, with the rostral projection 

 more or less produced, and the anterior edges irregularly waved. Anterior 

 pairs of coxal plates of moderate size, and generally smaller in male than 

 in female; 5th pair with the anterior lobe rather deep. Superior antennae 

 shorter than the inferior, and without any accessoiy appendage; both pairs 

 in male considerably prolonged. Mandibles with distinct, though rather small 

 and slender palps. Maxillae of the usual structure Maxillipeds with the 

 masticatory lobes oblong oval in form, reaching beyond the penultimate joint 

 of the palp, and armed on the inner edge with strong flattened spines, palp 

 comparatively small and narrow. Anterior gnathopoda somewhat stronger 

 than the posterior, with the propodos ovate in form, and densely clothed with 

 bristles on the upper edge. The 2 anterior pairs of pereiopoda rather unequal 

 in size, the 2nd pair being much smaller than the 1st; antepenultimate pair 

 generally strongly recurved and shorter than the 2 last pairs, which are 

 nearly of equal length, with the dactylus generally inverted. Branchial 

 lamellae in most of the species folded transversely. Last pair of uropoda 

 with the rami rather narrow, and edged with small spines. Telson not very 

 large, with the lateral edges unarmed, cleft very narrow, terminal lobes 

 subtruncated at the tip. 



Remarks. The present new genus includes most of the species 



formerly referred to the genus Atylus of Leach. As, however, the latter 

 genus was founded upon the arctic form, A. car hiatus Fabr., which in several 

 points distinguishes itself very markedly from the other species, I have felt 

 justified in restricting the Leachian genus to that form, and to comprise the 



