1898.] PROM THE SOUTH PACIFIC. 465 



p. 406; Henderson, ' Challenger ' Anom. p. iOo (1888); Heil- 

 prin, Proc. Ac. Nat. Sci. Phil. 1888, p. 320; Ortmann, Dec. 

 Schiz. Plankton Exped. p. 51 (1893) ; Zool. Jahrb. x. Syst. p. 280 

 (1897). 



Petrolisthes marginatus, Stimpson, Ann. Lye. Nat. Hist. vii. 

 p. 74 (1862). 



Petrolisthes leporinoides, Ortmann, Zool. Jahrb. vi. Syst. p. 263 

 (1892) ; Semon's 'Porschungsreisen in Austral.' v. 1, p. 26 (1894). 



Petrolisthes dentatus, Henderson, Tr. Linn. 8oc. Loud. 2, v. p. 426 

 (1893). 



Petrolisthes dentatus var., de Man, Zool. Jahrb. ix. Syst. p. 374 

 (1896), in part. 



Petrolisthes lamarcici var. asiaticus, Miers, Zool. ' Alert,' pp. 269 

 & 557 (1884). 



(3) Var. EUFESCENs (Heller), 1861. 



? Porcellana dentata, H. Milne-Edwards, H. N. Crust, ii. p. 251 

 (1837) ; Dana, U.S. Expl. Exped., Crust, i. p. 419 (1852). . 



Porcellana rufescens, Heller, Sitz.-Ber. Ak. Wiss. Wien, xliv. 

 p. 255, pi. ii. fig. 4 (1861); ' Novara ' Crust, p. 76 (1865); 

 ?Kossmann, Ergebu. Zool. Eeise, ii. 1, pp. 75-78 (1880). 



Petrolisthes dentatus, Stimpson, Proc. Ac. Nat. Sci. Philad. 1858, 

 p. 227 ; Haswell, Cat. Aastr. Crust, p. 146 (1882) ; Ortmann, 

 Zool. Jahrb. vi. Syst. p. 262 (1892). 



Porcellana {Petrolisthes) rufescens, Hilgendorf, Mon.-Ber. Ak. 

 Wiss. Berlin, p. 825, pi. ii. fig. 7 (1878). 



Petrolisthes lamarcici, Ortmann, Semon's ' Forschungsreisen in 

 Austral.' v. 1, p. 26 (1894), in part. 



The full synonymy which I have felt obliged to give for this 

 very variable species reveals the remarkable fact that it has been 

 described under no fewer than twelve names. In default, how- 

 ever, of any reliable separating character of specific value, I am 

 compelled to include all its various forms under one head. 



Colour is of course useless to us as a specific character. It is 

 here very variable, and its variations run coimter to those of other 

 characteristics. The extreme forms are on the one hand almost 

 white, and on the other dark red blotched with dark purple. The 

 P. speciosus of Dana comprised light-coloured forms with red or 

 purple spots. Some of these varieties are extremely beautiful. 

 Again the number, size, and arrangement of the teeth on the 

 inner side of the wvist of the chelae show great variations. But 

 the number increases with age, and the limbs of the two sides are 

 often different, so that any distinctions founded on these must 

 be abandoned. Extreme forms are : — (1) a wavy edge with a 

 large hump at the near end, and (2) the same edge bearing a row 

 of five well-defined teeth, with hints of a sixth. The teeth may be 

 sharp or blunt in otherwise similar forms, or may become bicuspid, 

 seemingly by two running together. Leach's orignal P. lamarclcii 

 had three teeth ; P. asiaticus Leach, P. leporina Heller, P. lepori- 

 noides Ortmann, P. armatus Gribbes, and P. gundlachii Guerin, 



