SOIIIZOPODA. 31 



PUopodf in the male agreeing in nil points with those of males of the genus 

 Amblyop.i. 



Tflm (Fig. 1G) not quite as long as the last segment of the pleon, triangular in 

 slta|ie, tapering evenly to a narrowly rounded apex, nenrly twice as long an broad at 

 its lase ; distal half of each lateral margin armed with nineteen spines, increasing in 

 length towards the apex, the terminal ones alxmt one-tenth of the total length of the 

 telson ; median scte absent. 



Uropoda broken on both sides, but the inner one poaMMM a single strong spin*- 

 on the ventral surface at the inner posterior angle of the otocyst 



Length of the single specimen, an apparently adult male, 13 mm. 



There can be little doubt, 1 think, that Dactylerythropa arcwita, Illig (190G), is 

 the same species as the present one. Minor differences, it is true, are to !< noticed. 

 For instance, the visual elements of the eye in Illig's species are represented as larger 

 and less numerous than in D. hodgsoni. It may le that in the former preservation has 

 caused the visual elements to mass in groups of more or fewer lenses, since in the 

 'Discovery' specimen, as the figure (Fig. 9) shows, the visual elements are not 

 regularly arranged, but more numerous in some places than others, an effect pmlmbly 

 due to the mode of preservation. 



Moreover, in D. arcvuiia, the telson is not quite so long compared with the 

 breadth at its base as in D. hodgsoni, and is furnished with only eighteen spines on 

 each lateral margin. But these differences are insignificant when compared with the 

 general agreement between the two species in most points. One or two characters 

 may be added to the above diagnosis from Illig's description and figures. 



Antennular peduncle long and rather stout, last joint the largest and nearly equal 

 to the combined length of the other two. 



Antennal scale slightly over-reaching the antenuular peduncle, about four times 

 as long as broad, outer margin entire, and terminating in a short spine beyond which 

 tin- apex of the scale is only slightly produced. 



Four species of this genus are now known, D. sarsi (Ohlin, 1901), D. thawnatvp* 

 and D. goniops, Tattersall (1907), and the present species. 



From the other three species, D. h^gsoni is at once distinguished by the shajte 

 of the eye. In D. sarsi the eye is acutely pointed in front ; in D. ttuiumati>ps it 

 is of quite peculiar form, with an outer equatorial membranous ridge, while in 

 D. goniops the eye is quadrangular rather than pyriform in shape. Otherwise the 

 four species are rather closely allied and form quite a distinct generic group to 

 themselves. 



Z>. hodgsoni is at present only known from very deep water in the Antarctic 

 Ocean. Illig's specimens were collected over a depth of 4000-5000 metres, while the 

 present specimen was dredged in 2030 fathoms (ca. 3700 metres). 



H 2 



