428 Dli- J. G. DE MAN ON CRUSTACEA CHIEFLr 



furrow near the articulation of the dactylus characteristic of Alpheus brevicrislatus, 

 and the carinse on the outer surface of the palm are neither described nor figured ia 

 the ' Challenger' E,eport. The dactylus of the smaller chela of ^. hrevicristatus has a 

 slenderer form. These two species are therefore certainly different. 



It is on the authority of Coutiere, who has compared the type ot A. brevirosirls, Oliv., 

 with the Leyden type of de Haan's A. rcfpux, that these two species are considered also 

 now by me as identical, though I may observe that in de Haan's A. rapax the upper 

 border of the larger chela presents no trace at all of the transverse groove near tlie 

 articulation of the dactylus which is characteristic of A. hrevirostris {vide Coutiere, I. c. 

 p. 230, fig. 281, and in Bull. Soc. Entom. Prance, 1898, p. 250, fig. 1), and that the 

 antennal scale reaches barely or not beyond the antennular peduncle. In my opinion it 

 would be preferable to consider A. rapax of Eabricius as identical with A. brevirosiris, 

 Oliv., for Pabricius's description is fully applicable to the latter. The two specimens, 

 apparently both males, of A. rapax, received from the Museum of Strassburg, seem at 

 first sight to belong to two different sjoecies. The larger specimen, which is 65 mm. long 

 from the tip of the rostrum to the end of the telson, fully agrees with the Leyden type 

 of A. rapax, de Haan, and ought thus to be referred to A. brevirostris, Oliv. Tlie other 

 specimen, however, 55 mm. long, belongs perhaps to that species which has been 

 described and figured by Spence Bate under the name of A. rapiax {I. c. p. 552, pi. 99. 

 fig. 1). It fully agrees with it, excejit the antennal scale, which, though a little longer 

 than the peduncles of the outer and inner antennae, has a less slender shape, being 

 proximally broader in proportion to its length, whereas the terminal spine barely reaches 

 beyond the tip of the scale. As regards the shape of the antennal scale and the peduncles 

 of both pairs of antennae, this specimen agrees with that of A. brevirostiHs, except that 

 in the latter the antennal peduncle extends a little beyond the tip of the scale. The 

 rostral carina, acute and strongly compressed between the eyes, does not reach so far 

 backward as in the other older specimen, but fades away soon behind the eyes. All the 

 legs are a little slenderer than in the specimen of A. brevirostris. Both the larger and 

 the smaller chela closely resemble those of Spence Bate's A. rapax. The larger chela is 

 29 mm. long and 875 mm. broad, the palm being 17'5 mm. long, the fingers 11'5 mm. ; 

 the smaller chela is 28 mm. long, the fingers three times as long as the palm, and the 

 greatest breadth of the chela, about in the middle, is almost one-fourth of its length. 

 The fact that the fingers are longer in proportion to the length of the palm than in the 

 ' Challenger ' species may be explained by the larger size of our specimen. Ortmann 

 referred both specimens to A. rapax, de Haaxi = brevirostris, Oliv. {teste Coutiere); 

 perhaps he will eventually prove to be right, if the length of the fingers of the smaller 

 chela of A. brevirostris is shown to be so very variable. 



The two egg-laden females from the Inland Sea of Japan are of equal size, adult, 

 55 mm. long from the tip of the rostrum to the end of the telson. The rostrum reaches 

 in one female almost to the distal end of the first joint of the antennular peduncle, in the 

 other only to the middle of this joint; it passes into a carina, which between the eyes is 

 sharp, strongly compressed ; the upper edge, between the eyes slightly concave, runs 

 obliquely upward and, reaching the upper surface of the carapace, becomes obtuse, even 



