88 



of the form, previously described by Baird as Canthocamptus furcatus, a species 

 which is undoubtedly closely allied to, if not identical with, that recorded by 

 Philippi. Boeck was the first to call attention to this fact, and therefore restored 

 the Philippian genus, which is now generally accepted. The genus is chiefly 

 characterised by the comparatively simple structure of the oral parts, and by the 

 peculiar penicillate appearance of some of the spines issuing from the outer ramus 

 of the 1st pair of legs. It seems to comprise numerous species, which, however, 

 are so closely, related that they were not recognized as such by earlier carcino- 

 logists, but only as accidental varieties of the same species. To Dr. Th. Scott 

 is due the statement by a careful anatomical examination, that these supposed 

 varieties in reality ought to be considered as distinct species, since their distinc- 

 tive characters have proved to be perfectly constant and independent of external 

 conditions. Dr. Scott has described 6 different species from the Scottish coast, 

 and I have myself been enabled to distinguish no less than 9 Norwegian species, 

 to be described below. The genus seems to be represented in all parts of the 

 oceans, and I have even found one or two species of this genus in the Cas- 

 pian Sea. 



52. Idya furcata (Baird). 



(PL LI, PL LII, fig. 1). 



Canthocamptus furcatus, Baird, Brit. Entomostraca, p. 210, PL XXV, figs. 1 & 2, PL XXX, 



figs. 16. 



? Syn: Idya barbigera, Philippi. 



Specific Characters. Female. Body moderately slender, with the anterior 

 division, seen dorsally, regularly oval or elliptical in outline, being evenly nar- 

 rowed both in front and behind. Urosome about half the length of the anterior 

 division and gradually tapered behind, genital segment very distinctly divided in 

 the middle. Caudal rami scarcely as long as the anal segment, outermost and 

 innermost apical setse comparatively short, the latter somewhat angularly ben! 

 at the base. Anterior antennae of moderate length and gradually tapered 

 distally, 2nd joint exceeding the 3rd in length, 4th joint shorter than either o:' 

 these joints, terminal part about twice the length of the 4th joint. First pair o:' 

 legs with the outer raraus extending somewhat beyond the 1st joint of the inner, 

 2nd joint of the latter but slightly attenuated, last joint very small, with th*' 

 apical claws comparatively short and somewhat unequal, the one quite smooth, 

 the other penicillate at the tip. Last pair of legs with the inner expansion of 



