FROM THE INLAND SEA OF JAPAX. 437 



sitviated still a little fai'ther from the second than the second from the fourth, is a little 

 smaller than the second ; the first and the second are placed upon the carapace, the 

 third reaches for the greater part of its length beyond tlie anterior margin of the 

 carapace; the second, third, and fourth teeth are a little larger than the following, 

 wtiich decrease in size, and the anterior tooth is a little farther from the pointed tip of 

 the rostrum than from tlie penultimate. In the other specimen the formula is 1+8 ; 

 the second tooth is very little farther from the fifth than from the first or gastric 

 tooth, and the latter is also somewhat smaller than the second ; the following teeth are, 

 as in the other specimen, equidistant, the two or three foremost are a little smaller 

 than the preceding, and the anterior tooth is twice as far from the penultimate as 

 from the acuminate tip, which is directed horizontally forward ; two teeth are on the 

 carapace, the third is situated above the anterior border. The lateral carinas of the 

 rostrum do not reach beyond the anterior border of the carapace. The postrostral ridge 

 is distinct, and extends until quite near the posterior margin of the carapace. The 

 sulcus gastro-frontalis (Stimpson) is indistinct in both specimens, as are also the 

 cardiaco-branchial grooves ; the antennal and the gastro -hepatic sulci are well developed, 

 and the antero-lateral part of the cervical groove, situated just below the hepatic spine 

 and beginning, at some distance from the anterior border of the carapace, at the 

 posterior end of the antennal carina, is rather deep but short, being hardly once and a 

 half as long as its distance from the anterior border. The outer angle of the orbital 

 margin is produced into a sharp though small tooth ; antennal and hepatic spines well 

 developed, the former a little the larger. Pterygostomian angle angular, though not 

 produced into a tooth or spine. Stridulating-organs wanting. 



Characteristic of this species (PI. 33. fig. 57) is a fissure about in the middle of the 

 lower margin of the first segment of the abdomen, distinctly visible in Spence Bate's 

 fig. 1 of Penceus anchoralis, which is identical with Pen. ctiriiirostris. In both specimens 

 the second segment of the abdomen carries a short median carina as far from the anterior 

 as from the posterior margin of this segment ; the carina of the third segment reaches 

 from the posterior margin to the anterior fourth part, the carinte of the fourth and 

 fifth terminate in a narrow cleft at the posterior extremity, but the carina of the third 

 segment does not ; the carina of the sixth segment, which is little longer than broad, is, in 

 the specimen 78 mm. long, posteriorly more strongly curved backward than in the other. 

 The telson, which is very little longer than the sixth segment, but one-third shorter than 

 the outer swimmerets, terminates (fig. 58) in an acuminate pointed tip ; it is deeply 

 grooved in the middle of the upper surface, and the lateral margins carry four movable, 

 very small spinules ; the foremost or tirst spinule is inserted at little more than one-third, 

 the posterior or fourth at one-seventh the length of the telson fi'om the posterior 

 extremity, the second is inserted just midway between the first and the fourth, and the 

 third immediately in front of the fourth ; the fourth is twice as large as the third, and 

 the two anterior are a little larger than the third. Stimpson describes the telson as 

 similar to that of de Haan's Pen. monoceros, where it is armed with three minute 

 spinules, and Kishinouye describes it likewise : Ortmann (Spengel, Zool. Jahrb., Syst. v. 

 1890, p. 447) was therefore apparently wrong when denying their existence altogether ', 



U2* 



