14 R. NORRIS WOLFENDEN. 



RHINCALANUS GRANDIS. 

 R/tincalanus grandis, Giesbrecht, ' Belgica ' Rep., p. 18. 



? 7'2-S'O mm. Head produced in front, dorsally roughly triangular in shape, 

 with large lateral swellings at the base, rostrum not visible from behind. The cephalo- 

 thorax is over six times as long as the abdomen, which is composed of three segments. 

 A pair of short spines on the anterior margin of the third thoracic segment, and a pair 

 of strong and longer spines on the fourth segment, differentiate this species from nasutus, 

 also the absence of any spines on the abdominal segments. The first pair of feet have 

 the Ri and Re of only two segments, Re three with two marginal spines ; other feet 

 (except the fifth) have three-jointed rami. 



The fifth pair, of one branch only on each side, with three segments, have on the 

 second segment a long inner marginal bristle, and on the last segment three bristles of 

 nearly equal length, two apical, of which the outer is the thickest and the middle one a 

 little the longest, and one on the inner distal margin. A short spine is present on the 

 outer margin in its upper third. The anterior antennae are about six joints longer 

 than the furca. Adult males were absent. 



These examples are absolutely identical with Giesbrecht's species. 



METRIDIA (BOECK). 



One of the most remarkable things about Brady's ' Challenger ' Copepoda is the 

 omission of mention of any example of this genus from his report. Distributed 

 throughout the Atlantic from the North to the South Pole, and in the Pacific, and 

 throughout the track followed in the Atlantic and Southern Ocean by the ' Challenger,' 

 the absence of mention of any species of this genus is certainly extraordinary. In the 

 northernmost regions Metridia longa occurs (Sars, Norwegian North Polar Expedition) 

 throughout the Faroe Channel and the Atlantic trough as far south as Valentia in 

 Ireland ; and south of the Wyville Thompson ridge, M. lucens, normani and curticauda 

 (Wolfenden) ; while south of Lat. 40 and throughout the Atlantic occur M. curticauda, 

 brevicauda, princeps and venusta ; but south of Kerguelen appears a new and charac- 

 teristic species, M. gerlachei, which replaces all others. This is the representative 

 species of the South Polar seas, and it appears abundantly in the ' Gauss,' ' Discovery,' 

 and ' Belgica ' collections, and it is as characteristic of this area as M. longa and lucens 

 are of the northern cold area. M. princeps occurs seldom, and M. brevicauda as a 

 straggler, outside its proper area of distribution. 



