216 Part III. — Twenty-fifth Annual Report 



Notodelphyidse* ; while Dr. Canu, referring to the distribution of this 

 species, speaks of it as occurring in the Mediterranean, the English 

 Channel (Manche), and the North Sea.t Dr. G. S. Brady records the 

 occurrence of one or two specimens of Nolopterophorus elongatus 

 amongst some things sent to him by the Rev. A. M. Norman, but which 

 were lost during examination and before they were described and 

 figured.* Possibly the form described here should be referred to the 

 same species, and ultimately this may be necessary. Meantime, however, 

 I am inclined to identify it with the form described by M. Hesse. 



In the figure of Noiopterophorus elongatus given by Dr. Bucholz 

 (fig. 6a, pi. viii.) in the work referred to in the footnote, the dorsal 

 appendages are without whip-like filaments ; and the excellent drawings 

 of the same form in plate xxiii. of Dr. Giesbrecht's Beitrage represent 

 these appendages as bearing minute hairs instead of the long filaments 

 seen in N. papilio. 



Tribe Caligoida. 



Fam. Caligidae. 



Genus Nogagus, Leach (1819). 



Nogagus latus, sp. n. PI. xv., figs. 1-9 (cJ). 



This species and the one to be immediately described are both males, 

 and are for the present referred to the genus Nogagus, Leach ; they were 

 observed on dog-fishes captured in the North Sea. 



The genus Nogagus is not a satisfactory one, and though meantime 

 allowed to stand, is not considered valid. The various forms that have 

 been included in this genus are all of them males, and are supposed to 

 belong to other genera, of which the females only are known, i.e., 

 Pandarus, Leach, Dinemoura. Baird, Echthrogaleus, Stp. and Liithk, 

 etc., and a few of them have already turned out to be the males of such 

 genera. 



The males and females of those species that have already been satisfac- 

 torily identified — as, for example, Pandarus carcharice, Leach (the female), 

 and Nogagus Cranchi, Van Beneden (the male) — are so unlike each other, 

 not only in general appearance, but also to some extent in structure, that 

 it is difficult to believe, without having sufficient proof of their identity, 

 that they can belong to the same species. Yet it seems to be the case, in 

 these examples at least, that the difference between them, though so 

 pronounced, is only sexual, and due probably to a difference in the 

 habits of the animals, the male perhaps living a more free life than the 

 female, 



Steenstrup and Liitken divided the Nagagi into two groups, the chief 

 differences between them being that in the first the urosome (abdomen) 

 and both branches of the first four pairs of thoracic feet consist of two 

 articulations, while in the second the urosome and both branches of the 

 fourth pair of feet are uni-articulate. 



One of the forms now to be described— the one named above — appears 

 to be referrable to the first group, but the other differs slightly from 

 both. 



*" Beitrage zur Kenntniss einiger Notodelphyiden." Mitth. ZooL, Stat. Neapel, 3 

 Band, pp. 327, 328, taf. xxii.-xxiv. (1882). 



f " Les Copepodes du Boulonnais." Trav. du Laborat. de Zool. Mar. des^Wimereux- 

 Ambleteuse (Pas-de-Calais), Tome vi., p. 191 (1892). 



X '' British Copepoda," vol. i., p. 144. 



