216 STALK-EYED CRUSTACEA. 



In s;iiiall individuals of this species the rounded lateral expansions of the 

 carapace behind the antennal spines are more prominent and the antennal 

 spines relatively smaller than in full grown specimens. 



G. willcmoesii was discovered by the naturalists of the " Challenger" Expe- 

 dition in 1874. Two specimens were procured south of Amboina, lat. 4° 21' 

 S., long. 129' r E. ; depth, 1425 fathoms. 



Gnathophausia brevispinis Wood-Mason. 

 Plate J. 



Onathophauna gracilis, var. brevispinis Wood-Mason, Ami. Mag. Nat. Hist., 6th Ser., VII. 18S, 1891. 

 Oiiathophausia brevispinis Wood-Mason, Ann. Mag. Nat. Hist., 6th Ser., VIII. 269, 1891. 

 Gaathophausia dentala Fax., Bull. Mus. Comp. Zool., XXIV. 217, 1893. 



Rostrum somewhat shorter than the remaining part of the carapace, 

 slender, gently up-curved, its three margins armed with teeth, those of the 

 superior margin the largest. At the base of the rostrum, over the anterior 

 part of the gastric region, rises a prominent thin triangular crest, produced 

 at the apex to a spine ; there are in most specimens a minute denticle near 

 the anterior, and one to three near the posterior, end of the crest. Supra- 

 orbital spines small, not distinctly defined from the base of the rostrum. 

 Antennal spines of moderate length, slender and acute. Branchiostegal 

 spines very long, their bases expanded into wing-like processes on each side 

 of the carapace. Cervical groove distinct. Dorsal keel obsolete on the 

 posterior gastric region, distinct behind the cervical groove and armed with 

 a row of small teeth. Posterior dorsal spine rather short, scarcely projecting 

 beyond the first abdominal somite ; it is directed upward at a much stronger 

 angle than is conunon in this genvis. Near the infero-posterior angles of the 

 carapace are two spines, the upper of which is long and slender, equalling 

 die dorsal spine in length, while the lower one is reduced to a tooth, obsolete 

 in some specimens. The lower lateral keel is distinct, terminating in the 

 upper of the two spines at the infero-posterior angle. Below this another 

 minutely denticulated submarginal keel runs from the branchiostegal spine 

 backward to the lower and smaller spine of the infero-posterior angle of the 

 carapace. The upper lateral keel is obsolete. 



The abdomen is rather slender, and is armed with a row of seven dorsal 

 spines ; two of these occur on the first segment, two on the second, and 

 one on each of the three following segments ; the two spines on the second 

 segment, together with the posterior spine of the first segment, are much 



