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



" Hypostome produced. 



" Upper Lip broad, cleft at the apex ; the lobes of unequal length. 



" Mandibles elongate, without molar tubercle or palp, apically very broad, much or 

 little dentate, not a uniform pair ; the left mandible having an accessory plate. 



" Lower Lip narrow, elongate, without inner plates, but furnished at the apex with a 

 dentate appendage (articulo appendiculari). 



" First Maxillse very broad ; outer plate apically furnished with strong but simple 

 spines (ungvibus) ; palp one- or two-jointed ; inner plate very broad, very setose. 



" Second Maxillse with the inner plate very broad, the outer narrow or very small. 



" Maxillipeds with very broad plates ; the outer plate furnished with weak teeth or 

 only serrate ; the palps slender, narrow ; the last joint of the palp unguiform. 



" Body very deep, but thick. Four anterior side-plates much increasing in size 

 (successively) ; the fourth side-plate very large. The head very short, but deep. 



" Antenna short, but robust ; the upper with a small secondary appendage ; the first 

 joint of the flagellum elongate and thick. 



" First and Second Gnathopods almost of the same shape and size, scarcely subchelate. 



" Third and Fourth Per^opods with the first joint little or not at all dilated. 



" Fifth Peraeopods shorter than the preceding ; the first joint much dilated and 

 elongate. 



" The Uropods each furnished with two cylindrical rami. 



" Telson little, sometimes slightly cleft." 



Genus Stegocephcdus,^ Kr0yer, 1842. 



Stegocephalus injtatus, Krdyer (PI. CXXXVII. A). 



1774. Cancel- ampulla, Pliipps, Voyage towards the North Pole, p. 191, Tab. xii. fig. 3. 

 1781. Gammarus ampulla, J. C. Fabricius, Species Insectorum. 



1 787. „ „ J. C. Fabricius, Mantissa Insectorum, torn. i. 



1788. Cancer (Gammarus) ampulla, Gmelin, Linnsei Systema Naturae, t. i. p. v. p. 2991. 

 1791. Gammarus ampulla, Olivier, Hist. Nat. Insectes, t. vi. 



1793. „ „ J. C. Fabricius, Entom. Syst., t. ii. 



1796. Cancer gammarellus ampulla, Herbst, Krabben u. Krebse, ii. No. 61, pi. 35, fig. 1. 



1802. Cancer Gammarus ampulla, Turton, Translation of Gmelin's Linnaeus. 



1802. Gamviarus ampulla, Bosc, Hist. Nat. Crust, t. ii. p. 146. 



1803. „ ,, Latreille, Histoire Naturelle, -vol. vi. 



1818. „ „ Latreille, Tableau EncyclopMique, pi. 348, figs. 1, 2, 3. 



1820. Cancer ampulla, Scoresby, An Account of the Arctic Kegions. 



1821. Gammarus ampulla, Sabine, Appendix to Parry's Voyage, p. 51. 



, 1824. ,, ,, Sabine, Supplement to Parry's Voyage, p. ccxxix. 



1828. „ ,, J. C. Eoss, Appendix to Parry's Narrative, p. 204. 



1835. „ „ Owen, Appendix to Sir J. Ross's Second Voyage. 



' For the original definition of this genus, see Note on Kr0yer, 1842 (p. 198). 



