NO.14S0. SCHIZOPOD CRUSTACEANS— ORTMANN. 39 



7. GNATHOPHAUSIA GRACILIS Willemoes-Suhm. 



Gnathophausia gracilis Willemoes-Suhm, Trans. Linn. Soc. London (2) I, 1875, 



p. 33, pi. ix, fig. 1. — G. 0. Sars, Forh. Selsk. Christiania, 1883, no. 11; Rep. 



Challenger, XIII, 1885, p. 48, pi. vn, figs. (i-10. 

 Gnathophausia gracilis var. brevispinis Wood-Mason and Alcock, Ann. Nat. Hist. 



(6), VII, 1891, p. 188. 

 Gnathophausia brevispinis Wood-Masox and Alcock, Ann. Nat. Hist. (0), VII, 



1891, p. 269.— Faxon, Mem. Mus. Comp. Zool., XVIII, 1895, p. 216, pi. .1. 

 Gnathophausia dentata Faxon, Bull. Mus. Comp. Zool., XXIV, 1893, p. 217." 



Carapace with keels and spines of the type of the first group, but 

 upper lateral keel entirely absent. Lower lateral keel terminating in 

 a spine at the postero-inf erior angle of the carapace. There is another 

 smaller spine just below this one, which is directed outward and some- 

 times obsolete. Median keel interrupted, its posterior part with spini- 

 form serrations. Postero-dorsal spine short. From the anterior end 

 of the posterior part of the dorsal keel a pair of oblique keels runs 

 forward and downward. Anterior part of dorsal keel triangularly 

 elevated upon the gastric region, forming a prominent dentate crest, 

 which extends forward to the rostrum. Supraocular spines small; 

 antennal spines larger; branchiostegal spines very large. 



Antenna! scale of the type of the second group, large, of usual 

 shape, formed by a lanceolate-ovate lamella, the outer margin of 

 which has a strong spine, which is serrated at the outer edge and pro- 

 jects slightly beyond the terminal lobe of the lamellar part. 



Abdomen of the general type of the second group, but peculiar on 

 account of the great development of dorsal spines. The first and sec- 

 ond segments have each 2 large, triangular spines in the median line, 

 the posterior of them at the posterior margin of the segment; the 

 anterior spine of the first segment is generally smaller than the pos- 

 terior. The following 3 segments (third to fifth) have each a posteri- 

 orly projecting spine on the posterior dorsal end. The two lappets 

 of the epimera of the first to the fifth segments are short and pointed, 

 the posterior slightly longer than the anterior. 



Epimera of the sixth abdominal segment of the type of the second 

 group, not united ventrall} T to form a ventral plate. There are 2 tri- 

 angular, pointed epimeral lappets on each side of the anterior part of 

 the sixth segment. 



I do not entertain the slightest doubt that G. brevisjjinis Wood- 

 Mason and Alcock, is identical with G. gracilis Suhm. Faxon admits 

 the following differences of G. brevispinis from G. gracilis: 



1. Prominent, dentate gastric crest. 



«The Gnathophausia figured on the colored plate opposite p. 500 in Chun, Aus den 

 Tiefen des Weltmeeres, 1900, resembles this species, except for the spine just back of 

 the cervical groove. 



öMem. Mus. Comp. Zool., XVIII, 1895, p. 218. 



