89 



different, and has been referred provisionally by the present author to another 

 family, viz., the Tachidiidce. The great fragility of the animal renders its exact 

 examination rather difficult, and has indeed given rise to the specific name 

 here proposed. 



Occurrence. Some specimens of this form, all of the female sex, were 

 found at Riser in depths ranging from 50 to 100 fathoms, muddy bottom. 



Gen. Pseudodetodes, G. O. Sars, n. 



Generic Characters. - - Body slender and attenuated, with strongly 

 chitinised integuments, and all the segments distinctly denticulate at the hind 

 edge. Cephalic segment peculiarly expanded below, and produced in front to 

 a well defined rostral projection. Urosome with the segments somewhat 

 expanded laterally; last segment .smaller than the preceding ones. Caudal 

 rami somewhat produced and rather narrow. Anterior antennae of moderate 

 size, but with the number of joints much reduced. Posterior antennas with the 

 outer ramus well defined, uniarticulate. Mandibular palp likewise uniarticulate. 

 Maxillae without any distinctly defined exopodal lobe. Anterior maxillipeds 

 with 3 setiferous lobes inside the basal part. Posterior maxillipeds moderately 

 strong. 1st pair of legs small, with both rami biarticulate; the 3 succeeding 

 pairs with the outer ramus distinctly triarticulate and very slender, inner ramus 

 biarticulate and shorter than the outer. Last pair of legs of rather a peculiar 

 shape, the proximal joint being remarkably produced both outside and inside, 

 distal joint comparatively small. 



Male unknown. 



Remarks. This genus also is only founded on a single species, which 

 however exhibits several very conspicuous peculiarities both as to the outward 

 appearance and the structural details, preventing its reference to any of the 

 hitherto known genera of the present family. 



73. Pseudodetodes typicus, G. O. Sars, n. sp. 



(PI. LXII). 



Specific Characters. Female. Body of rather slender form and gradu- 

 ally attenuated behind, with the segments rather sharply marked off from each 

 other. Cephalic segment of very large size, occupying rather more than half 

 the length of the anterior division, and forming below on each side a broad 



13 Crustacea. 



