ENTOMOSTRACA OF THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 307 



Caudal rami short. 



Habitat. South Orkney Islands ; collected in April 1903 ; Station 325, 60 43' 42" S., 

 44 38' 33" W. 



Remarks. This species differs from the last in the proportional lengths of some 

 of the joints of the antennules, and in the form and armature of the last pair of thoracic 

 legs. The other thoracic legs are also stouter. 



One obvious character by which Machairopus may be distinguished from Psamathe 

 is found in the armature of the outer branches of the first pair of thoracic legs. In 

 Psamathe the terminal spines of both rami are somewhat similar, while in Machairopus, 

 only the terminal spines of the outer ramus have their upper margins setiferous, as 

 shown in the drawings. 



Fam. THALESTRID.E. 

 Genus Parathalestris, G. 0. Sars, 1905. 



Parathalestris clausi (Norman). (PL II. figs. 15-18.) 



1869, Thalestris clausi, Norman, Brit. Assoc. Report (1868), p. 297. 



1880, Brady, Monogr. Brit. Copep., vol. ii. p. 128, pi. Ixii. figs. 1-12. 



1905, Parathalestris clausi, G. 0. Sars, Crust, of Norw., vol. v. p. Ill, pis. Ixv., Ixvi. 



A single specimen a male which undoubtedly belongs to this species, was obtained 

 in a tow-net gathering collected by the Scotia at Station 62 on 13th December 1902 ; 

 Station 61, 4 15' S., 33 38' W. ; earlier on this date, the vessel passed Rocas Light, 

 bearing WSW. about 30 miles, off the north-east coast of South America. 



From what is known concerning the distribution of this species, its occurrence so 

 far south appears to be somewhat unusual ; its presence in this gathering may have 

 therefore been accidental. It is moderately common round the British and Norwegian 

 coasts, and Dr Canu records it from the French coast. 



Parathalestris coatsi, new species. (PI. III. figs. 7-16.) 



Female. Body depressed and somewhat expanded ; thorax and abdomen not clearly 

 defined ; forehead broadly rounded, rostrum small, caudal rami short. Length of 

 specimen represented by the drawing about 1 mm. 



Antennules composed of nine joints ; the first four are tolerably large, but the 

 remaining five are small, their entire length being shorter than the second and 

 third combined. Antennae moderately stout, the outer ramus two- (or indistinctly 

 three-) jointed. 



The mandibles are moderately stout and provided with a small two-branched palp 

 (fig. 10). Second maxillipeds stout; end joint short and armed with a strong and 

 curved terminal claw which is furnished with a few minute spines on its inner edge ; 

 the end joint, to which the claw is articulated, has also a few minute spines on the 

 margin on which the claw impinges (fig. 11). 



The first pair of thoracic legs are stout and of moderate length ; their outer ramus 



(ROY. SOC. KDJN. THANS., VOL. XLVIJI., 553.) 



