292 DR THOMAS SCOTT ON THE 



The male differs from the female by the peculiar structure of the right antennule, 

 the fifth and sixth joints of which are produced exteriorly into angular and gibbous 

 expansions. The seventh joint is elongated and slender, while the base of the next one 

 extends inwards into a horn-like projection nearly at right angles to the joint, but curved 

 slightly forward and having its inner edge finely serrated. The remaining joints are 

 slender and moderately elongated, except the last one, which is short ; the articulations 

 between the fifth and sixth and the eighth and ninth joints are hinged (fig. 1). 



The fifth pair of thoracic legs in the male are asymmetrical, that on the left side 

 is long and slender and terminates in a claw-like spine, while the basal part of the 

 proximal joint expands anteriorly into a short angular process. The other foot is also 

 elongated, but the end joints are dilated and form a thumb-like arrangement, as shown 

 in the drawing (fig. 5). 



Habitat. — This species was obtained in gatherings from Stations 64, 65, 67, and 

 93, 6° 30' S., 34° 25' W., to 30° 05' S., 45° 28' W. 



Calanopia americana was obtained by Dr Dahl in a collection of plankton from 

 the mouth of the river Tocantins, on the north-west coast of South America, where the 

 water was doubtless more or less brackish. Its occurrence in the Scotia collections, 

 besides extending the distribution of the species considerably, is interesting, from its 

 having been found in the open sea. 



Genus Lahidocera, Lubbock, 1853. 



Labidocera nerii (Kroyer). 

 1848, Pontia nerii, Kroyer, Naiurh. Tulsdr. (N.S.), vol. ii. p. 579, Taf. 6. 



This was a tolerably common species in the Scotia collections. It occurred in no 

 fewer than twenty-eight gatherings, extending from Station 7, 26° 23' N., 20° 20' W., 

 in the North Atlantic, to 95, 32° 15' S., 47° 30' W., in the South Atlantic, occurring at 

 nearly regular intervals. 



Labidocera acutifrons (Dana). 

 1849, Pontella acutifrons, Dana, 02}. cit, vol. ii. p. 30. 



The only gatherings in which this species was obtained were collected at Station 

 14, 21° 28' N., 22° 40' W., and Station 18, 19° 59' N., 23° 34' W. 



Genus Pontella, Dana, 1849. 



Pontella atlantica (M.-Edw.). 

 1840, Pontia atlantica, M.-Edw., Hist. Nat. Crust., vol. viii. p. 420, Taf. 39. 



This species occurred in gatherings from Stations 7, 35, and 41, 26° 23' N., 20° 

 20' W., to 5° 40' N., 26° 4' W., but only a few specimens were observed. 



(ROY. SOC. EniN. TRANS., VOL. XLVIII., .')38.) 



