838 THE VOYAGE OF H.M.S. CHALLENGER. 



three years may be required for full development. " Neither Goes," he says, " nor 

 Boeck has been successful in figuring the species ; especially in the work of the latter 

 author the head with the rostrum is quite erroneous, while it is precisely the character- 

 istic form of this part of the body that is the best mark of distinction between Oediceros 

 lynceus and Oediceros microps, which in many respects stand extremely near together." 

 The figures given by Goes seem to agree with the form microjjs as to the head and the 

 form lynceus as to the telson ; it is possible, therefore, that Goes had a form inter- 

 mediate between the other two, which are recognised both by Sars and Schneider as 

 extremely close to one another. The mouth-organs in the Challenger specimen closely 

 agree with the account given by Schneider in regard to Oediceros lynceus, but whereas 

 he says that in the mandibles both plates are divided into six or seven tolerably acute 

 teeth, I find on the left mandible the secondary plate divided into five rather strong 

 teeth, and on the right mandible more weakly constructed, with numerous denticles, 

 only the lowest of which deserves to be called a tooth. " In the first maxillae the 

 outer plate has two shorter furcate and five longer serrate spines ; the inner plate is 

 broadly oval with one simple and one plumose seta at the apex." Schneider calls 

 attention to the fact that Boeck speaks of two plumose setse. It is possible that there 

 may be some variation between individuals in these minute details ; thus, in the 

 Challenger specimen, on one of the maxillas one of the furcate spines has an additional 

 tooth by the side of the shorter arm of the fork. In the lower antennse the gland-cone 

 is narrow and produced. On the telson, besides the two spinules at the flattened or 

 slightly insinuate apex, there is on each lateral margin a little cilium above the rounded 

 apical corner, and a little above this cilium a group of two or three minute cilia, none of 

 these appendages being visible except under a tolerably high power of the microscope. 



Xoca/iV?/.— Station 49, south of Halifax, Nova Scotia, May 20, 1873 ; lat. 43° 3'N., 

 long. 63° 39' W.; depth, 85 fathoms; bottom, gravel, stones; bottom temperature, 35°*0. 

 One specimen. Dredged. 



Genus Halimedon, Boeck. 



1865. Oediceros (pars), Goes, Cnist. ampli. maris Spetsb., p. 11. 



1870. Halimedon, Boeck, Crust, amph. bor. et aret., p. 89. 

 1876. „ Boeck, Be Skand. og Arkt. Amph., p. 281. 



1882. „ Sars, Oversigt af Norges Crustaceer, p. 96. 



1883. „ Schneider, Norges Oedicerider, p. 32. 



1884. ,, Schneider, Crust, og Pycn. Kvaenangsfjorden, p. 91. 



1886. Monoculodes, Gerstaecker, Broun's Klassen und Ordnungen, Bd. v. Abth. ii. p. 502. 



For the original definition of the genus, see Note on Boeck, 1870 (p. 400). 

 Schneider, in 1883, gives the following definition : — 



" Side-plates of the thu'd and fourth pair very large, generally almost entirely 



