LUTKENIA ASTERODEBMI. 77 



end truncated and provided with three or four minute 

 apical spines. In the second and third pairs both rami 

 two-jointed ; the first joint of the outer ramus consider- 

 ably larger than the second; in the inner ramus the 

 first joint is the smaller one. In the fourth pair, also 

 biramose, both rami only one- jointed, the inner ramus 

 being very minute. 



Habitat. — Parasitic on Luvarus imperialis Raf. 

 Three specimens of this Luthenia were sent to the 

 Rev. A. M. Norman by Laughrin about 1863, which 

 had been obtained by him from a specimen of Luvarus 

 captured off Polperro, Cornwall. ('Crustacea of Devon 

 and Cornwall,' by Norman and T. Scott, 1906, p. 210.) 



Distribution. — Mediterranean ; apparently very rare 

 in the British Seas. 



Genus NOGAUS Leach, 1819* 

 Syn. Nogagus M. Edwards, 1840. 



The genus Nogaus is now generally regarded as unsatis- 

 factory. It comprises males only, some of which have already 

 been recognized as belonging to more than one genus, of which 

 the females had previously only been known ; and it is con- 

 sidered probable that as our knowledge of the Copepod para- 

 sites of fishes increases and their relationships and life-history 

 are better understood, all the males ascribed to Nogaus will ere 

 long be removed from it and the genus itself become obsolete. 

 There are however, a few of the Nogaus males whose relation- 

 ship is still doubtful, and it will be better to leave these 

 where they are till they can be disposed of satisfactorily. 

 Among these doubtful forms is the one described below. 



In Nogaus the frontal plates are without lunulse, but other- 

 wise the forms ascribed to this genus have a general resem- 

 blance to Galigus. Steenstrup and Liitken divided Nogatis (or 

 Nogagus) into two groups, the principal differences between 

 them being as follow. In species belonging to the first 

 group the four pairs of swimming legs are biramose, and the 

 rami are all two-jointed; the abdomen also is two-jointed. In 

 those belonging to the second group, while the rami of the 



* The name " Nogaus " was used by Dr. Leach in 1819 ; it was afterwards 

 changed to Nogagus l>y M. Edwards in 1840, but we find Dr. Baird still using 

 the original word " Nogaus " in his ' British Entomostraca ' at p. 282 ; and 

 C. B. Wilson in his recent work on ' North American parasitic Copepods of 

 Pishes' also adopts this form of the name. 



