NOKTH ATLANTIC SEA ANP THE FAR(iE CHANNEL. 11 



o 



pansions like C. IviiKrhorciis. The anterior antennae of twenty-five 

 joints are much longer than the whole body. The first pair 

 of feet have an extraordinary double-hooked process on the dorsal 

 surface of the second basal joint, an upper and lower hook placed 

 vertically, the latter very strong and prominent. (PI. IX., figs. 1 

 and 2.) The structure of tiie mouth organs is very similar to Calcnuis. 

 In both cases it was an adult female, with well-developed symmetrical 

 genital segment. The only described Copepod at all resembling it is 

 the C. princcps of Brady {Challenger JRi^ort, "Copepoda"), in which the 

 feet are very similar, but there are no such setre on the anterior foot- 

 jaws as Brady figures, the maxilla is totally different as regards its 

 bristles, and the segmentation of the anterior antenna3 and abdomen is 

 also different. It is therefore certainly not Brady's species. The latter 

 cannot be a Calanus, as is evident from the presence of three external 

 spines on the last segment of the exopodite of the swimming feet. 



2. Eucalanus atlanticus {nov. sp). In the course of dissecting many 

 examples of the well-known E. elongatus <? , I have come across a good 

 many specimens which to all outward appearance resemble E. elongatus, 

 except that the larger furcal segment, and longest tail seta, are on the 

 left side instead of the right side (Giesbrecht had already noted the 

 irregularity in this respect of the females). But together with this 

 condition the oral organs are not retrograded, as in the 3' elongatus, and 

 resemble entirely those of the female. The exopodite of the posterior 

 antenna is longer ; the first joint of the endopodite is not twice as long 

 as the second joint, and is only two and a half times as long as broad ; 

 the mandible palp is longer (three times as long as broad), and divided 

 by the origin of the exopodite into two nearly equal parts, and a normal 

 masticatory plate is retained with the usual teeth. (Plate IX., fig. 4.) 

 In the maxilla all the inner lobes are retained as in the ? , while in 

 E. elongatus <? they have disappeared. The anterior and posterior foot- 

 jaws are also normal as in the $ . The left fifth foot is only a little 

 longer than the right, the first segment of the exopodite of each foot 

 has a short marginal bristle, the last joint of the left side two distal 

 bristles, the right foot three distal bristles. (PI. IX., fig. 3.) In size 

 (4-45 mm. to 4-50 mm.) the animal is equal to the adult S of E. elongatus. 



In various species of jEtidvinm, while in the last adult stage many 

 males possess fully developed fifth feet together with retrograded oral 

 organs, the stage antecedent to the last is one in which the fifth feet 

 are imperfectly developed, while the oral organs are retained as in the 

 female. This I have proved to be the case in many instances, and the 

 fact accounts for many discrepancies of authors in the description of 

 males with immature fifth feet. I do not know, however, if the 



NEW .SEUIES. — VOL. VII. NO. 1, H 



