CRUSTACEA NORTH PACIFIC EXPLORING EXPEDITION 20I 



Genus DIOGENES Dana 



We submit the following amended character of this genus : 

 Ophthalmic ring exposed between the bases of the eye-peduncles, 

 and armed with a bracteole which is often produced and rostriform. 

 Aciculum or basal scale of the external antenna broad at the base 

 and sometimes bifid ; flagellum ciliated. Chelipeds unequal, the left 

 larger, with the commissure between carpus and hand vertical and 

 marginal : hand short and broad, oblique ; the fingers oblique, with 

 calcareous, acuminate tips. Dactyli of the second and third pairs of 

 of feet long. 



The species are inhabitants of the warmer seas, and are most 

 numerous among the Asiatic islands. The following is a list of the 

 species already known : 



D. miles Dana D. spiiiifrons (De Haan )Stm. 



c:(stos Dana edzcardsii (De Haan) Stm. 



diiiphauiis ( Fabr. ) vStm. arenarius (Lucas) Stm. 



312. DIOGENES CUSTOS (Fabricius) Dana 



Pagiirus ciistos Fabricius, Milne Edwards, Hist. Nat. des Crust., 11, 236. 

 Diogenes custos Dana. 



Taken at Port Jackson. Australia. 



313. DIOGENES BREVIROSTRIS Stimpson 

 Plate XIX, Fig. 2 



Diogenes brez'irosfris Stimpson, Proc. Acad. Xat. Sci. Phila., x, p. 24^ 

 [S3]. 1858. 



Carapax much smoother than in D. custos, but somewhat rough- 

 ened at the sides. Lateral margin of the anterior region armed with 

 five or six spinules. Ophthalmic rostrum smooth, and much shorter 

 than the ophthalmic scales. The eyes, ophthalmic scales, and acicles 

 are nearly like those of D. edzvardsii. The teeth or points of the 

 frontal margins are all obtuse ; the lateral ones most prominent. 

 Great cheliped naked, roughened above with minute subspiniform 

 granules ; below glabrous, but obsoletely granulated ; superior mar- 

 gin of carpus and hand serrated with small teeth, ten in number, on 

 the carpus ; hand with an oblique, infero-posterior crest on the outer 

 surface, armed with seven or eight small spines ; inferior margin of 

 hand sharp-granulated ; dactylus longitudinally costate above, costse 

 granulated. Right or smaller cheliped hairy ; carpus grooved above. 



