FROM THE INLAND SEA OF JAPAN. 393 



somewhat shorter postero-lateral nearly at the level of the median part of the cervical 

 groove, i. e. a little hehind the middle of the carapace. TJie upper surface shows here 

 its greatest breadth of 6'5 mm. ; the proportion between this breadth and the length 

 fully agrees with that of the dimensions indicated by Stimpson. The likewise granulated 

 postero-lateral borders are also slightly arched, converging backward, but, different 

 from Tritodynamia (confer Nobili, in ' xlnnales Mus. Nat. Hungarici,' iii. 1905, tab. 10. 

 figs. 1 & 2), their concave side is turned inward, in Tritodynamia, however, outward. 

 The postero-lateral borders almost reach to the posterior margin of the carapace. From 

 the j)oint where the antero- and postero-lateral borders meet, a granulated line proceeds 

 backward on the side wall of the carapace, terminating above the antepenultimate legs ; 

 it is here that the carapace has its greatest width of 7 "2 mm. 



The upjjer surface, which is one-third broader than long, is slightly convex longi- 

 tudinally; the median transverse groove, which is situated a little behind the middle 

 and occupies about one-third of the breadth of the carapace, is broad and shallow ; 

 but the gastric region, which regularly curves into the strongly defiexed front, is barely 

 demarcated from the hepatic regions. Whereas the larger anterior half of the cardiac 

 region is slightly convex longitudinally, a shorter posterior part is somewhat depressed. 

 Just in front of the posterior margin of the carapace, parallel with it, a straight ridge 

 runs between the bases of the last pair of legs ; at its lateral extremities this ridge 

 curves forward and, running above the last pair of legs, appears here granular. The 

 carapace is also slightly arched from side to side. Its upper surface is finely punctate, 

 for the rest smooth ; examined under the microscope it appears very finely granulate 

 (" subtilissime granulata," Stimpson). 



The distance, 3'7 mm., between the external orbital angles, which are not at all promi- 

 nent, measures almost three-fifths of the greatest breadth of the upper surface and three- 

 fourths the length. The upper orbital margins regularly curve into the latei'al margins 

 of the front, which converge forward, so that the much defiexed front appears somewhat 

 broader at its base than at its anterior border ; the anterior border is 1-28 mm. broad, 

 about as broad as the orbits and one-fflh of the breadth of the upper surface ; at its 

 base, however, the breadth of the front is almost one-third the greatest width of the 

 carapace. When the latter is looked at from above the anterior margin of the front 

 appears very slightly arcuate, but when the f lont itself is looked at from above the 

 anterior margin appears broadly triangiUar, because it projects a little forward in the 

 middle ; the lateral margins of the front make distinct, somewhat obtuse angles with 

 the anterior border. The frontal and supraorbital margins are smooth ; frontal median 

 furrow short and quite shallow. 



Interantennular septum very narrow, if complete ; antennular fossa) barely broader 

 than long, well developed, like the antennuloe, which fold transversely (PI. 31. fig. 4). 

 The basal joint of the outer antennae, situated between the basal antennulai-y joint and 

 the small obtuse tooth at the inner lower angle of the orbits, is about as long as broad; 

 the second joint, which is just as long, but only half as broad, reaches to the level of the 

 front, and the much smaller third joint extends beyond it ; the flagellum is 1-65 mm. 

 long, longer than the breadth of the anterior Ijordor of the front, and reac'iing bevond 



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