NO. 1480. SCITTZOPOD CRUSTACEANS—ORTMANN. 39 



7. GNATHOPHAUSIA GRACILIS Willemoes-Suhm. 



Gnalho]/h((iisi(i gmcilis Willemoes-Suhm, Trann. Linn. 80c. London (2) I, 1875, 



p. 33, pi. IX, fig. L— G. O. Sars, Forh. Selsk. Christiania, 1883, no. 11; Rep. 



Challenger, XIII, 1885, p. 48, pi. vii, figs. 6-10. 

 Gnathophaima f/racilis var. brerispims Wood-Mason and Alcock, Ann. Nat. Hist. 



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

 Gnnthophausia brevispinis Wood-Mason and Alcock, Ann. Nat. Hist. ((>), Vll, 



1891, p. 269.— -Faxon, Mem. Mus. Comp. Zool., XVIII, 1895, p. 216, ]>!. .t. 

 Gnathophaufiia de7iiataFAX0'{^, Bull. Mus. Comp., Zool., XXIV, 1893, p. 217." 



Carapace with keels and spines of the tj^pe of the first oroup, but 

 upper lateral keel entirely absent. Lower lateral keel terminating in 

 a spine at the postero-inf ei'ior ang-le 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 triang-ularl}^ 

 elevated upon the g-astric region, forming- a prominent dentate crest, 

 which extends forward to the rostrum. Supraocular spines small; 

 antennal spines larger; branchiostegal spines very large. 



Antennal 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 slightl}^ be3^ond the terminal lobe of the lamellar part. 



Abdomen of the general t3'pe 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 ventrally 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 doul)t that G. hrev!sj>!n!s ^Vood- 

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

 the following diti'erences of G. hrevl.y)mis from G. graeH/s: 



1. Prominent, dentate gastric crest. 



«The Gnathophamia 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. 



ft Mem. Mus. Comp. Zool., XVIII, 1895, p. 218. 



