ME. G. S. BRADY ON THE PELAGIC ENTOMOSTRACA. 33 



two of these being from Messina, the other from the North Sea. 

 There can, I think, be no reasonable donbt, that the latter is the 

 species referred to by Goodsir, and I therefore here retain the 

 original name as having the claim of priority. The chief char- 

 acters by which Dr. Claus distinguishes his northern species, 

 C. Helgolandicus, from the southern C. longiremis, are the dis- 

 tribution of setae on the apical joints of the upper antennge 

 (fig. 11) and the presence, in the former species, of a serrated 

 inner border to the basal joints of the fifth pair of feet (fig. 12), 

 In these particulars the species here recorded agrees with C. Hel- 

 golandicus. It is one of the commonest forms on our coast, 

 occurring abundantly both in pelagic and littoral situations. 



Genus. CALANUS, Leach. 

 Fifth thoracic segment indistinct, united with the fourth. 

 Superior antenna 25-jointed, sometimes (two of the joints being- 

 soldered together) 24-jointed ; those of the male thickened but 

 not hinged. Inferior antenna and maxillary organs like those of 

 Cetochilus. Fifth feet consisting of one branch ; those of the 

 male nearly alike ; sometimes altogether absent in the female. 

 Abdomen of the male composed of five ; of the female, of four (or 

 three) segments. Eyes simple, small. 



1. Calan/tts Clausii, n. sp. PI. I, figs. 1-11, 13. 



Body elongated, about one-twentieth of an inch long (without 

 the tail setse), colourless and fragile. Superior antennae 24-jointed, 

 (the eighth and ninth of the twenty-five joints being fused toge- 

 ther, ) a little longer than the cephalothorax ; the two terminal 

 articulations contracted at the base and somewhat swollen at the 

 distal extremities : the upper or outer edge is beset with short hairs, 

 and the joints in the male are irregularly swollen, the third to 

 the sixth or seventh having each a stronger and longer hair than 

 the rest. Inferior antennce two-branched, the secondary branch 

 with four short median articulations. Cephalothorax oval in 

 outline, rounded above, the last segment conspicuously indented 

 or umbilicate at its junction with the abdomen. Swimming feet 

 slender, the inner branch two, the outer three-jointed, except the 

 first pair, the inner branch of which has only one (?) joint. Fifth 



D 



