FEOM THE INLAND SEA OF JAPAN. 419 



with the anterior. Sis specimens are of subequal size, their lensjth from the tip of the 

 rostrum to the end of the telsou varying between 50 and 56 mm. ; the seventh is younger. 

 38'5 mm. long : the first six specimens are thus a little longer than was indicated by 

 Stimpson, viz. 44 mm. The slender, stilifovm rostrum is horizontal and straight, or tlie 

 distal half is slightly turned upward ; the free portion of the rostrum is once and a half 

 as long as the upper border of the carapace, rarely a little shorter, and one-fourth or one- 

 fifth of it extends beyond the antennal scales. The upper margin, which arises with an 

 obtuse carina a little before the middle of the carapace, carries in four adult specimens, 

 in which the rostrum is normally developed, 7, 8, or 9 teeth. These teeth, which are 

 rather small and tioo of which are always (also in the other specimens) situated on the 

 caraj)ace, reach either almost to the middle of the free part or a little beyond it, so that in 

 one specimen the terminal part, which is devoid of teeth, appears a little longer tiian the 

 rest, whereas in the others the terminal third or a little more appears unarmed. Two or 

 more distal teeth are longer than the preceding ; in one specimen they gradually increase 

 in length, but in the others this is not the case, and the longer distal teeth are of equal 

 or unequal length. This species is apj)arently variable as regards the number and the 

 shape of these teeth. The lower margin is armed, in these four specimens, with 8, 

 10, or 12 teeth, that reach to the tip ; they are partly larger than the teeth of the upper 

 border, and grow also, more or less regularly, longer towards the tip. The basal part 

 of the lower margin, posterior to the first tooth, is nearly straight. In these four 



2 2 2 2 



specimens the toothing-formulae are therefore: jq, ^, g, and pj ; in two others, in wliich 

 the rostrum is apparently not well developed, reaching not or barely beyond the 



2 2 2 



antennal scales, the f ormulse are : -r- and t, ; in the young specimen, finally, it is .y 



2 



10-12 



Stimpson mentions - j^^ as the toothing-formula, but in not one of our specimens do ten 

 or twelve teeth occur on the upper border. Neither the upper nor the lower margin of 

 the rostrum is ciliated. 



Carapace and abdomen are smooth, though finely punctate. Antennal tooth slender, 

 reaching to the middle of the basal joint of the outer antennae ; antero-lateral angle 

 rounded, devoid of a pterygostomiau spinule. Abdomen rounded, the third segment 

 moderately produced backward in an obtuse lobe. The pleurae of the third segment are 

 rounded posteriorly, those of the fourth are obtuse, but the fifth are produced, at tlie 

 postero-lateral angle, in a sliarp spine. Measured along its upjoer border, tlie sixth 

 segment appears almost twice as long as the fifth, resembling that of Spirontocaris stylus 

 (Stimps.) {of. Rathbun, ' Decapod Crustaceans of the North-west Coast of North 

 America,' 1904, p. 84). The sixth segment, the lower surface of which is rounded, and 

 the postero-lateral angles of which terminate in a sharp tooth, is just twice as long as 

 broad in the middle. The telson, which is a little longer than the sixtli segment and a 

 little more than four times as long as broad at its base, tapers rather strongly ; its 

 rounded upper surface, armed, according to Stimpson, with G pairs of spinules, carries in 

 the six adult specimens 5 pairs, though in one of them there are G spinules on the left 

 and 5 on the right side ; the telson of the young individual has but 4 pairs. The telson 



SECOND SERIES. — ZOOLOGY, VOL. IX. GO 



