169 



that the antennuiae are provided with 6, instead of 4 sensory filaments. Colour 

 greyish white, less pellucid than in H, Mengii. Length of adult female 4 mm. 



Remarks. The present species was at first wrongly identified by Mr. 

 Budde-Lund with H. elegans, Schobl, which is the same as H. Mengii, Zaddach; 

 hut was subsequently recognised by the same author as a distinct species, and 

 described under the above name. According to him, the H. Mengii of Dr. Weber 

 is the present species, and not that of Zaddach. Though very nearly allied to 

 that form, it is easily distinguishable from it by the rather different sculpturing 

 of the dorsal face, and by the complete absence of the 2 conspicuous dorsal pro- 

 minences occurring in H. Mengii on the 3rd segment of the metasome. It 

 also grows to a rather larger size. 



Occurrence. I have found this form in great abundance in 2 places in 

 the neighbourhood of Christiania, both located in the so-called Ladegaardso. It 

 occurred here in loose mould beneath leaves and decaying pieces of wood. I have 

 also received some few specimens of this form from conservator Storm, who col- 

 lected them in the neighbourhood of Trondhjem. In habits, it exactly agrees 

 with H. Mengii. 



Distribution. Denmark, Holland. 



Fam. 3. Oniscidae. 



Characters. Body oval or oblong, with the lateral parts of the segments 

 more or less expanded. Metasome with the 2 anterior segments rather small, 

 and having the epimeral plates concealed; last segment much narrower than the 

 preceding ones, and conically produced at the end. Eyes generally well developed, 

 compound. Antennuiae very small, with the apical sensory appendages short, 

 papilliform. Antennae, as a rule, slender, with the flagellum pauciarticulate. 

 Buccal mass not very prominent below. Mandibles with the cutting part highly 

 chitinized and, as usual, composed of 2 superposed dentate lamellae, behind which 

 is a membranous hairy lappet and a varying number of penicils, molar expan- 

 sion obsolete, without any triturating surface, it being replaced by a brush-like 

 recurved seta. Anterior maxillae with the outer masticatory lobe very strong and 

 coarsely spinous at the tip, inner lobe much narrower and provided with only 2 

 hairy bristles. Posterior maxillae distinctly bilobed at the tip, and having the 

 outer edge angularly produced near the base. Maxillipeds with the basal part 



22 Crustacea. 



