AMPHIPODA OF THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 483 
Thaumatelson mermis, sp. nov. (Pl. I. figs. 16 and 17.) * 
South Orkneys, Scotia Bay, Station 325; 9-10 fathoms. April and May 1903. 
Several specimens, the largest 3 mm. long. 
Specific Description.—Very similar to T. herdmani Walker, but differing in having 
the second gnathopod long and chelate, the propod being produced into a long acute 
process as long as half the whole propod, the fixed finger finely pectinate and fitting 
closely against the dactyl, which has its inner margin furnished with small, widely 
separated serrations. 
Further Description.—The form described above is the female, several of the speci- 
mens examined bearing eggs. The lateral angle of the head is rather acute ; and in the 
shape of the body, the proportions of the segments and of the side plates, the species 
closely resembles 7. herdmani. The eye is fairly. large, round, and colourless in spirit, 
having been probably red in the living animal. In the first antenna the first joint is 
large and produced at its upper distal angle, though to a slightly less extent than in 7. 
walkeri, and I can find no accessory flagellum. In other respects the antenna is similar 
to that of ZT. herdmanz, and the joints of the flagellum bear long sensory sete. In the 
lower antenna the last joint of the peduncle is about as long as the preceding, and the 
flagellum is of the same length. The mandible has the palp small, the first joint is 
short, the second moderately long, the third small and slender, the cutting edge and 
other parts having the character common to the family. The first maxilla has the 
palp two-jointed, its extremity furnished with four or five small spinules and one or 
two longer setze ; the inner lobe is rounded at the end, and bears three or four sete ; the 
outer lobe bears several stout spinules and one or two longer sete, and has its imner 
margin furred. The second maxilla is of the ordinary form. | 
The maxillipeds have the inner lobes separate, rounded at the end, and bearing 
two rather large sete. The outer lobe is small, being merely a slight extension of the 
joint as in Metapoides sarsw. ‘The palp is similar to that in 7. herdmani. 
The first gnathopod (fig. 16) has the side plate undeveloped; in general shape it 
is similar to that of 7. herdmam, but has both the merus and the carpus produced 
posteriorly into a lobe tipped with long sete, the process of the merus reaching to the 
end of that of the carpus. The propod is rather large, and is slightly distended at the 
palm, which is nearly transverse and is defined by three or four stout spinules. 
The second gnathopod (fig. 17) has the basal joints similar to those of 7. herdmanz, 
but is chelate, as already described. The pereeopoda are long, very slender, and bear 
few sete or spinules. The side plates of the fourth pair are particularly large, and 
cover up the fifth, sixth, and seventh pairs, the side plates of which are not developed 
and the basal joints slender. ‘The first uropod extends considerably beyond the second ; 
the branches are subequal, shorter than the peduncle. The second uropod is short, but 
extends beyond the third and a little beyond the telson; its branches are subequal. 
* This species is perhaps the same as Thawmatelson nasutwm Chevreux (Bull. Muséum Hist. Nat., 1912, No. 4, 
p. 5), though the descriptions of the mandibular palp do not agree. 
