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



Genus 1. Lophogaster, M. Sars, 1856. 



Lophofjaster, M. Sars, Forliandl. Skand. Naturf., Mode i Cliristiania, 1856, p. IGO. 

 Ctenomysis, Norman, Rep. Brit. Assoc, 1861, p. 151. 



Generic Characters. — Carapace distinctly sculptured, forming anteriorly a broad 

 tridentate frontal plate, posterior margin deeply emarginate in the middle, leaving last 

 segment of trunk wholly exposed above, lateral wings produced, pointed. Caudal 

 segments with well-defined lamellar epimera, last segment subdivided by a transverse 

 suture. Eyes globular, partly covered by the frontal plate. Antennular peduncle very 

 short and thick, inner flagellum small, outer remarkably strong and elongate. Antennal 

 scale cordiform, outer edge serrate, inner setose. First pair of maxillse without any 

 palp, second pair with only two masticatory lobes ; palp comparatively small. First pair 

 of legs (gnathopoda) with terminal joint obtusely rounded and densely hirsute. The 

 remaining legs rather robust, with strongly developed dactylus. Branchiae tripartite, the 

 branches regularly bipinnate, and each pinnula exhibiting a double series of small 

 leaflets. Telson produced, with apex entire, and armed with strong terminal spines. 

 Outer plate of uropoda not subdivided at extremity, outer edge straight, and terminating 

 in a small dentiform projection. 



Remarks. — In the above diagnosis I have made an attempt to arrange together several 

 characters, that in my opinion should be regarded as peculiar to the present genus, when 

 compared along with the three new genera brought to light by the Challenger Expedition. 

 The genus which, as that first established, may be taken to be the type of the family, is 

 as yet represented only by a single species, Lophogaster typicus, formerly regarded 

 exclusively as a northern form, but now having also been met with during the Challenger 

 Expedition, proved to exhibit a very wide geographical distribution. 



1. Lophogaster typicus, M. Sars (PI. 1. figs. 1-7). 



Lophogaster typicus, M. Sars, Forhandl. Skand. Naturf., Mode i Cliristiania, 1856, p. 160. 

 Ctenomysis alata, Norman, Rep. Brit. Assoc., 1861, p. 151. 

 Lophogaster typicus, M. Sars, Univ. Progr., 1862. 



Of this interesting Schizopod, fully described by the late Professor M. Sars, there are 

 three more or less complete specimens in the Challenger collection, from two Stations, at 

 no great distance apart, both south of the Cape of Good Hope. One of the specimens is 

 a full-grown male, the other two (one of which is defective) are females. 



I have most carefully compared these specimens with the form occurring on the 

 Norwegian coast, without, however, having detected any distinctive character warranting 

 the assignment of specific diiference, and henc6 I am obliged to regard them as 

 belonging to the typical species, notwithstanding the remarkable fact of their occurrence 

 in a locality so widely distant from the Norwegian Sea. 



