126 THE VOYAGE OF H.M.S. CHALLENGER. 



species, the geniculate bend between the meral and carpal joints reaching to the middle 

 only of the autenual scale. 



The telson (sec fig. 3) is very elongate and slender, with the apex acutely pointed 

 and the subapical spines smooth. 



The uropoda (ibid.) have the inner plate very considerably produced Ijcyond the 

 outer, and reaching to the tip of the telson. 



Habitat.- — All the specimens in the collection were taken in the tow-net at the 

 surface of the sea. The following is a list of the localities : — 



As regards distribution, the species would therefore appear to be wholly confined 

 within the soutliern hemisphere, inhabiting, as it does, exclusively the Antarctic and 

 South Atlantic Oceans. 



Genus 6. Nematoscelis, G. 0. Sars, 1883. 



Nematoscelis, G. 0. Sar.s, Preliminary Notices on the Challenger Schizopoda. 



Generic Characters. — Form of Iwdy and structure of eyes and antennae almost as in 

 Thysanoessa. Mandibular palp very small. Terminal joint of second pair of maxillae 

 hkewise exceedingly minute. Maxillipeds slender, with last joint somewhat appressed 

 and densely setose at the inner edge ; epipodite obsolete. First pair of legs remarkably 

 elongate and slender, well-nigh filiform, with a bunch of spiniform setae at the apex, but 

 for the rest almost naked. The four succeeding pairs of legs rather short and thick, 

 with the terminal part not nearly attaining the length of the meral joint. Penultimate 

 pair of legs very small, with the endopod bi-articulate. Last pair of legs quite rudi- 

 mentary, forming only a lamellar setiferous plate (exopod). The two anterior pairs of 

 gills simple, and of a similar structure to those in Thi/sanoessa ; remaining pairs composed 

 of two distinct branches ; last pair by far the largest. Ovisac simple, flattened. 

 Luminous apparatus of the usual structure. 



Remarks. — ^This genus is most nearly allied to Thysanoessa, but difi'ers, among other 

 characteristics, very materially in the structure of the legs, the first pair of which are 



