36 PllOVEEDINdS OF THE NATIONAL MUSEUM. vol. .xxxi. 



4390._i female. Off Santa Catalina Islands, 1,350 to 2,182 fathoms. 

 4528.— 1 male. Monterey Bay; 545 to 800 fathoms. 



Pn'iu'oit.-i records. — Arafura Sea, SOO fathoms (Sars); vicinity of 

 TahiLir Island, S. of INIindanao, Philippines, 500 fathoms (Sars); 

 Hawaiian Islands: Kaiwi Channel, and vicinity of Kauai Island, 

 •11:2-881 fathoms (Ortmann); Bay of Bengal, 1718 fathoms (Wood- 

 Mason). 



5. GNATHOPHAUSIA GIGAS Willemoes-Suhm. 



Plate II, tigs. \h, I'l. 



Gnathopluvrn'm (jigai^ Willemoes-Suii.m, Trans. Linn. Soc. London, Zool. (2), I, 

 1875, p. 28, pi. IX, figs. 16, 17; pi. x, figs. 2, 3.— G. O. Sars, Forh. Selsk. 

 Christiania, 1883, no. 4; Rep. Challenger, XIII, 1885, p. 33, pi. in.— Ort- 

 mann, Bull. U. S. Fish Comm. for 1903, Pt. 3, 1905, p. 968. 



This species is closely allied to G. calca/rata., but differs in certain 

 constant characters. On account of the general resemblance of both 

 species, it is hardly necessar}^ to give a complete description of G. gigas, 

 and it will suffice to mention the differential characters. 



1. The arrangement of the keels of the carapace is essentially the 

 same in both species, with the exception that the posterior oblique 

 keels of the upper face are entirely wanting in G. gigas. The 

 anterior oblique keels are present, occupying the same position as in 

 G. calcarata. 



2. The spines of the carapace, in young specimens, are aliout the 

 same as in G. calcarata, but the supraocular spine is more distinct, 

 and as large as, or even larger than, the antennal spine. In older 

 individuals all the spines are shorter than in G. calcarata.^ wdth the 

 exception of the supraocular, which is always distinct. Antennal 

 spir^e small, branchiostegal generally slightly larger than the latter, 

 postero-dorsal very short. The largest are the postero-inf erior spines, 

 which approach closely those of G. calcarata.^ although they are 

 shorter in the average. 



3. Antennal scale of G. gigas oi slightly different shape; itisrathei 

 lanceolate, and not ovate, and the terminal point is longer and more 

 tapering. The outer margin has four or five spiniform serrations, 

 the anterior sharp and strong, the posterior small and sometimes obso- 

 lete; these serrations, generall}", are stronger than in G. calcarata. 



4. The epimera of the five anterior abdominal segments are differ- 

 ent in both species. While in G. calcarata both lappets of the second 

 to fifth are strongl}- developed and are both spiniform, in G. gigas 

 only the posterior lappet is produced and spiniform in all five seg- 

 ments, and the anterior is small and rounded (see Sars''s fig. 1 on 

 Plate HI). 



5. The ventral cpimeral plate of the sixth abdominal segment differs 

 in both species in the larger individuals. In 3'oung specimens of G. 



