662 ROCEEDINGS OF THE NATIONAL MUSEUM. 



In some respects C. montezum.ee dugesii shows an approach toward 

 this species, but the two forms can not be confounded on account of 

 the greater slenderness of G. chapalanus, the great length of the ros- 

 tral and postorbital spines, etc. C. shufeldtii is distinguished from C. 

 chapalanus by the presence of lateral spines on the carapace, broader 

 rostrum, differently shaped male appendages, etc. 



Genus ASTACUS Fabricius (s. s.). 1 



< Cancer Linnaeus, Syst. Nat., 10th ed., I, p. 625, 1758. 



< Astacus Fabricius, Syst. Entomol., p. 413, 1775 ; Species Insectorum, I, p. 514, 



1781; Mantissa Insectorum, I, p. 331, 1787; Entomol. Syst. emend., II, p. 478, 

 1793; Suppl. Entomol. Syst., p. 382, 1798. 



< Astacus Latreille, Considerations Generates, p. 101, 1810 (Astacus fluviatilis 



Fabricius = Cancer astacus Linnaeus, specified as the type, p. 422). 



< Astacus Leach, Edinh. Encycl., VII, p. 398, 1814; Trans. Linn. Soc. London, 



XV, pp. 336, 343, 1815. 

 <^ Potamobius Leach, Samouelle's Entomologist's Useful Compendium, p. 95, 

 1819 (Type, Potamobius fluviatilis = Cancer astacus Linjsleus). 



< Astacus Milne-Edwards, Hist. Nat. Crust., II, p. 329, 1837. 



= Astacus (subgenus) Erichson, Arch. f. Naturgesch., 12ter Jahrg., I, p. 90, 1846. 

 Type, Cancer astacus Linnaeus. 



The genus Astacus, as first established by Fabricius, 2 included eight- 

 een species. The dismemberment of this heterogeneous assemblage 

 was begun by Fabricius himself in 1781, 3 by the removal of three 

 species to the genus Squilla. In 1798, 4 he eliminated several other 

 species from Astacus, forming for their reception the genera Crangon, 

 Alplieus, Palcemon, and Palinurus. As left by its founder in 1798, the 

 genus Astacus contained only five of the original species, namely, A. 

 marinus ( = Cancer gammarus Linnaeus), A. fluviatilis ( = Cancer 

 astacus Linnaeus), A. ccerulescens, A. fulgens, and A. norvegicus. Two 

 of these, ccerulescens and fulgens, are indeterminable. In 1810 Latreille, 5 



'Those who accept the genera defined by polynonrialists after the year 1758 will 

 ascribe the genus Astacus to Gronovius, 1764 (Zoophylacium Gronovianuin, Fascic- 

 ulus II, p. 227). Even as early as 1760 Gronovius (Acta Helvetica, IV, p. 23) assigned 

 Galatea strigosa polynomially to Astacus, using Astacus in its old pre-Liunaean sense. 

 In 1772 Pallas, a binomialist, in his "Spicilegia Zoologica," Fasciculus IX, p. 81, used 

 the combination Astacus clauuricus in treating of the Daurian crayfish. Pallas wrote 

 in Latin, and it is evident that Astacus was here used merely as the Latin word for 

 "crayfish" or " lobster," and not as a technical generic name ; for the diagnosis of the 

 Daurian crayfish is beaded " Descriptio Cancri danurici," conformably with Linn.eus's 

 nomenclature. Even if one forces the point and carries the genus Astacus back to 

 Pallas, 1772, it will not make the Daurian crayfish the type of the genus, since the 

 description of the Daurian crayfish is a comparative one, the lesser European Asta- 

 cus \_Asfacus nostras minor'], i. e., Cancer astacus Linnaeus, serving as the standard for 

 comparison. To regard as a type the thing compared, rather than the standard of 

 comparison, would be a manifest absurdity. 



9 Syst. Ent., 1775. 



"Species Insectorum. 



4 Suppl. Ent. Syst. 



"Considerations Go'ne'rales sur l'Ordre Natnrel des Animaux composant les Classes 

 des Crustaccs, des Arachnides, et des Iusectes. 



