178 THE VOYAGE OP H.M.S. CHALLENGER. 



of the peduncle of the upper antennae, and the want of a finger and other peculiarities in 

 the second gnatliopods, were peculiarities so marked in the three species that he proposes 

 a new genus for them, thus defined: — "An onyx: pedunndus antennarum superiorum 

 crassissimus, oval is; inferiorummidto gracdior, eijliiidrieus ; (pculi magni*) ; p)edes primi 

 paris breviores, pjarmdo instructi ungve ; 2^6des seeundi paris sat elongati, f/raeillhni, 

 ungve carenies (quhiqveaiiicidati), cjusque vice ad finem articuli qiH'nti midtis validisquf- 

 preedifi setis." To this generic character, he says, may also be added, that the head in all 

 the species is tolerably small, and partially concealed by the first side-plates, a rostrum 

 projects in the middle in a little blunt point, formed by the small lateral excavations for 

 the insertion of the antennse, while the trunk is pretty strongly compressed, though 

 dorsally rounded. Though not considering the mouth-organs of use for generic characters, 

 he mentions that the mandibles are strong, furnished along the inner edge with three 

 dental tubercles (Tandknuder), meaning, to judge by the figure, a divided tooth at the tip 

 of the cutting edge and a small molar tubercle ; the upper rim shows near the outer angle 

 a tolerably deep incision ; the palps are tolerably short. The second maxillae have the 

 lower lobe (inner plate) very small, furnished at the extremity with some long, plumose 

 setae. The niaxillipeds have the palps long, the inner terminal plates narrow, linear. A 

 footnote to the words " oculi magni " explains that a species otherwise in agreement with 

 the genus need not be excluded merely on account of its having small eyes. 

 He next describes " Gammarus Sahiiii Leacb," commonly known now as Aji/athilla xabini, but 

 in my view having a claim to the title Amathilla homari, J. C. Fabr. He expresses surprise 

 tliat it should have escaped the notice of [Otto] Fabricius, and calls attention to the very 

 considerable differences between the young and adults, and the necessity for naturalists to 

 take such variations into account if they would avoid the groundless multiplication 

 of species. The next species described and figured, Gammarus loricatus Sab., has by 

 Spence Bate been named GammaracmitJms loricatitg, Sabine. The new species figured 

 and described as Gammarus pingvis is now called Amathilla pinguis. " Gammarws 

 Locusta, Montagu," is judged to be the commonest of all the Greenland Amphipods, and 

 to be undoubtedly identical with 0. " Fahricius' s On\&cviS, jjulex (n. 231 pag. 2.54)." The 

 suggestion is offered that it may be identical with Cancer nugax and Gammarus nugax in 

 the English travels, dating "from Phipp's time." " AmpMthoe carinata Ehrdt. 

 (Tab, II, fig. 6)," is next described. This, which is the Gammarus carinatus of Fabricius, 

 now bears the name Atijlus carinatus given it by Leach. " Amphiihoe Hystrix. (Acantho- 

 soma Hystrix Owen). Tab. II, fig. 6 [7]).," next described, has been identified by 

 Boeck with Lepechin's species, under the name Acantlwzone cuspidata, but the distribu- 

 tion of the species, according to the accounts of Lepechin, Kr0yer and Boeck, makes the 

 identification doubtful. In describing the flagellum of the upper antennae, Kr0yer remarks 

 that, with exception of the four first joints, which are all furnished with hairs at the end of the 

 lower edge, of the remainder, as a rule, only every alternate one exhibits hairs. Conse- 

 quently, he says, those joints without hairs easily escape observation and cause dis- 

 crepancies in counting the total number of joints. From the alternation just mentioned 

 and from the considerable length of individual flageUum-joints in young individuals, he- 

 argues that the increased number of these joints in the adults results, not from the 

 budding forth of new joints, but from the subdivision of the old ones. His descrip- 

 tion of the species in brief is: — "Amphithoe Hystrix: f route nan rostrata ; antennis 

 sup)erioribus dimidiam inferiorum paHem non sqvantibus; oculis orbicularibus, convexis; cor- 

 pore parum compresso ; annulis thoracis, tribusque abdominis aiiterioribus series aculeorum 

 qvinqve prxbentibus ; primo thoracis annulo prx ceteris aculeato, cornu gerente procumbens 

 et ad caput prominens ; epimeris femori solito minus appressis, plerumque in aculcus 

 productis ; manibus linearibus, ungula prxditis minuta ; aprpendice caudali unica, postice 



