EEPOET ON THE SCHIZOPODA. 77 



The antennal scale (fig. 5), but very slightly projecting beyond the second joint 

 of the antennular peduncle, exhibits an oblong-ovate form, its greatest breadth equalling 

 about one-third of the length. The apex is abruptly truncate, '5\dth the outer corner 

 unarmed and well-nigh forming a right angle. The basal spine, projecting beneath the 

 scale, is very strong, and extends far beyond half its length ; it is armed at the inner 

 edge with a row of fine denticles. The basal part of the flagellum reaches to the apex 

 of the scale, and is rather strong, with the two outer joints uniform in size. 



The mandibular palp (see figs. 9, 11) scarcely attains the length of the mandible 

 itself, and is specially distinguished by the middle joint being furnished (exclusive of 

 the usual marginal setse) with numerous short, spiniform bristles, arranged partly in a 

 double series along the inner side. 



The first pair of maxillge (fig. 12) have the exognath comparatively small, and of an 

 oval form. 



The second pair of maxillse (fig. 13) are distinguished more particularly by the short 

 and broad form of the terminal joint, which, moreover, exhibits anteriorly (apart from 

 the usual setse) a row of diminutive spiniform bristles similar to those on the mandibular 

 palp. 



The maxillipeds (figs. 14, 15), the legs (figs. 16-19; PI. XL fig. 12), and the gills 

 (PL XIL figs. 19-22 ; PL XL figs. 9, 11) exhibit the structure characteristic of the 

 genus. 



The copulatory appendages projecting from the inner plate of the two first pairs of 

 pleopoda in the male (see PL XL fig. 4) are very powerfully developed. Those on the 

 anterior pair (PL XIL fig. 28) jut out into three strong processes, the two outer of 

 which are highly chitinised, and bent in the form of hooks ; one of them has the apex 

 simple-acuminate, whereas the other expands at the tip into a serrate oblong plate. The 

 appendages to the second pair of pleopoda (fig. 29) branch out into two soft, irregularly 

 lobular processes, reaching far beyond the tip of the principal plate. 



The telson (see fig. 27) is very slender and elongate, almost equalling in length the two 

 posterior segments taken together, and has the ajjex produced to a lanceolate point. The 

 subapical spines are strongly developed, reaching far beyond the tip of the telson, and 

 diverging from each side ; they are also finely denticulate along their inner edge. More- 

 over, on the upper face, anterior to the point of insertion of the subapical spines, occur 

 two pairs of minute denticles, placed at some distance from each other. 



The uropoda (ibid.) do not nearly attain the tip of the telson, and have the inner 

 plate rather longer than the outer, but very much narrower. 



Colour. — Dana states that this form, in a living state, is quite pellucid, without any 

 conspicuous pigmentation; and hence he suggested the specific name "peZ^wcicZa." The 

 solitary specimen also, taken by myself off the Norwegian coast, and at first described as 

 Thysanopoda bidentata, exhibited a perfect transparency throughout the whole body. 



