CRUSTACEA XORTH PACIFIC EXPLORING EXPEDITION 17 



between large males and those of ordinary or small size, as men- 

 tioned by De Haan. 



The diversity in the shape of the rostrum in Xaxia serpuUfera and 

 A^ dicantha does not seem of sufficient importance to warrant a 

 generic separation. The deep orbits, with peculiar fissures widening at 

 the bottom, are characteristic of both, although in X . dicantha the 

 inferior fissure is much broader than in the other species. There is, 

 however, in the Japanese species a notch in the margin of the meros 

 of the hectognathopod at the insertion of the carpus, while in N. 

 scrpiiUfcra. judging from Guerin's figure, that margin is entire. 



Xaxia dicantha was taken by the expedition at the following local- 

 ities : Hongkong harbor, abundant on shelly bottoms in lo fathoms; 

 Northern China Sea, in 20 fathoms ; Kagoshima Bay, Japan, in 20 

 fathoms, shelly bottom. 



Genus SCYRA Dana 



14. SCYRA COMPRESSIPES Stimpson 

 Plate III, Fig. 4 



Scxra coinprcssipcs Stimpson, Proc. Acad. Nat. Sci. Phila., ix, p. 218 

 " [25], 1857. 



Carapax irregularly ovate; proportion of breadth to length, i :i.27 

 (rostrum and lateral spines included). It is rather depressed pos- 

 teriorly, well contracted between the hepatic and branchial regions. 

 Gastric region ample, rounded above, and nearly smooth, with the 

 exception of two or three minute tubercles along the median line 

 and one on either side posteriorly. There is a sharp tubercle on each 

 side at the hepatic region, and a short, sharp spine, extending hori- 

 zontally and somewhat curving forward at the summit of each 

 branchial region. Cardiac and intestinal regions rather small and 

 only moderately elevated. Posterior margin with a slightly prom- 

 inent tubercle at the middle. Rostrum scarcely as long as broad, 

 laminiform, scarcely contracted at base; horns shorter and less acu- 

 minate than in S. acittifrons. Praeorbital tooth prominent and acute, 

 but rather short. Parts about the head below much as in S. acuti- 

 frons. The tooth forming the external angle of the orbit is deeply 

 concave below, leaving the orbit at that point widely interrupted. 

 Margin of the pterygostomian region with three small, obtuse, lobe- 

 like teeth; a deep sinus separates this margin from that of the side 

 of the carapax. Feet all much compressed. Aleros of chelopoda 

 four-sided or prismatic, obtusely tuberculated along the angles ; 

 superior edge with blunt teeth near the base, and one prominent 



