i89 



Without ample material, such as only Miss Rathbun may dispose of, it is impossible 

 to discriininate the genera and species of the group. Nearly all genera are very obscurely 

 known, most of the species are not figured at all. 



The Prionoplacinae^ like the Pseudorhombilinae^ but apparently even at a higher degree, 

 are nearly related to Xanthid genera, such as Panopcus and Galene. The characteristic diagnostic 

 feature of the group, which I am, for want of material, unable to appreciate fuUy, consists in 

 the abdomen of the d being narrow, the third segment, and a plus forte raison the second, 

 distinctly falling short of the breadth between the bases of the posterior legs, and narrower than 

 the first segment. 



The following is an account of the genera of the present group in chronological order : 



Prionoplax H. Milne-Edwards, Ann. Sc. Nat. (3), t. 18, 1852, p. 163. Species: P . spinicarpus 

 (See Arch. Mus. Paris, t. 7, 1853, p. 167, pi. 11, f. 3). Hab. unknown. A second 

 species is P. ciliata Smith (Transact. Connecticut Ac, v. 2, 1870, p. 160) from Panama. 



Speocarcitms Stimpson, Ann. Lyc. Nat. Hist. New York, v. 7, 1862, p. 59. Species: S. caroli- 

 nensis (1. c, p. 59, pi. i, f. i — 3; Rathbun, Buil. Lab. Nat. Hist. State Un. lowa, 

 V. 4, 1898, p. 281 ; Buil. U. S. Fish Comm. for 1900, v. 2, 1901, p. 11, textfig. 2). 

 Several additional species have afterwards been added: S. granulimanus Rathbun, 

 Proc. U. S. Nat. Mus., v. 16, 1893, p. 242, S. californiensis Rathbun, Harriman 

 Alaska E.xp., v. 10, 1903, p. 190, pi. 9, f. i, 5. ostrearicola Rathbun, Proc. U. S. 

 Nat. Mus., v. 38, 191 1, p. 545, p. 48, f 2. The type species is West Indian, the 

 two ne.xt species are from California, and S. ostrearicola comes from Peru. 



Euryplax Stimpson, Ann. Lyc. Nat. Hist. New York, v. 7, 1862, p. 60. Species: E. nitida. 

 Literature and description : Rathbun, Buil. U.S. Fish Comm. for 1900, v. 2, 1901, 

 p. 8. Hab. West India. Second species: E. polita Smith (Transact. Connecticut Ac, 

 v. 2, 1870, p. 163) from Panama. 



Eiicratopsis Smith, Amer. Journ. Sc, v. 48, 1869, p. 391 ; Transact. Connecticut Ac, v. 2, 

 1870, p. 35. .Species: Eiicratc crassiinamis Dana, which, according to Stimpson's 

 researches (Journ. Nat. Hist. Boston, v. 7, 1863, p. 588) is generically distinct 

 from DE Haan's species Eiicrate crenata. Afterwards Eucratoplax elata A. Milne- 

 Edwards (Buil. Mus. comp. Zool. Harvard Coll., v. 8, 1880, p. 18) has been added 

 to Eticratopsis by Miss Rathbun (Buil. Lab. Nat. Hist. State Un. lowa, v. 4, 1898, 

 p. 281). Hab. West India and Rio de Janeiro (?) 



Glyptoplax Smith, Transact. Connecticut Ac, v. 2, 1870, p. 164. Species: G. p^ignax from Panama. 

 Probably this genus is more nearly related to Panopeus and so to the Xanthidae. 



Panoplax Stimpson, Buil. Mus. comp. Zool. Harvard Coll., v. 2, 1871, p. 151. Species: P. 

 depressa from West India. .See also : Rathbun, Buil. U. S. Fish Comm. for 1900, 

 V. 2, 1901, p. 12. 



Eucratoplax A. Milne-Edwards, Buil. Mus. comp. Zool. Harvard Coll., v. 8, 1880, p. 17. Species: 

 E. guttata from West India. A second species of Milne-Edwards {E. elata) seems 

 to belong to Eticratopsis. 



41 



sinoGA-ExrEDiTiE XXXIX c'. 25 



