AMPHIPODA OF THE SCOTTISH NATIONAL ANTAIMTIC KXPEDITION. 199 



Genus MKTOI>ELLA G. 0. Sars, 1892. 

 Metopella ovata (Stebbing). 



Mttopa ovata SuO.liing, 1888, p. 764, pi. xlii. 

 1906, p. 183. 



South Orkneys, .Scotia Bay, Station 325A ; dredge, 2-8 fathoms; temperature 

 29-30. Gth December 1903. Several specimens, none exceeding 3 mm. 

 in length. 



South Orkneys, Scotia Bay, Station 325; 9-10 fathoms. April 1903. Three 

 small specimens. 



Several of these are females bearing eggs, and none can be said to be certainly 

 males. These specimens agree closely with the description given by STEBBING, and 

 have the basal joints of the fourth and fifth peneopods narrowed as given in the 

 diagnosis of the genus. The gnathopods, uropods, and telson are all in close 

 agreement with the figures given in the Challenger Report ; the accessory flagellum 

 on the upper antenna is present, though extremely small, being about the same size as 

 in Metopoides sarsii Pfefifer. The palp of the mandible is short, and consists of a very 

 short first joint, an expanded second joint bearing three settu along one margin, and a 

 very short third joint tipped by a setum. 



Genus THAUMATELSON Walker, 1 90G. 



This genus was established by WALKER in 1907 for his species T. herdmani 

 obtained by the Discovery Expedition. The Scotia obtained several specimens from 

 the South Orkneys of what appear to be two additional species of the same genus. 

 The genus is mainly characterised by the very peculiar telson, which was described by 

 WALKER as "large, entire, oval, and set in a vertical plane on its longer edge." The 

 telson in the two species I have now to describe agrees well with this description. 

 The shape of the telson is probably associated with the extremely large side plates 

 which cover all the appendages when these are withdrawn, and enclose the animal so 

 that it looks like a small bivalve shell ; when this is done the pleon is folded in under 

 the side plates which appear to overlap the telson all except a small thicker ridge along 

 its dorsal margin, which fills the small slit between the right and left side plates. 



In the mouth parts the genus agrees well with the characters of the family Meto- 

 pidic ; one species, however, is peculiar in having the second gnathopod chelate. 



Thaumatelson ivalkeri, sp. nov. (PI. I. tigs. 11-15.) 



South Orkneys, Scotia Bay, Station 325. April and May 1903. Several 



specimens, the largest 3 mm. in length. 



Specific Dcxcri/'tion. In general characters (see fig. 1 1 ) similar to T. herdmani, but 

 with the side plates even larger, the fourth segment being longer than any of the others 



(ROY. soc. EDIN. TRANS., VOL. XLVIII., 4M.) 



