[30] Dr. Hagen in his “Monograph of the North American Astacidæ,” enumerates six species; _A. Gambelii_, _A. klamathensis_, _A. leenisculus_, _A. nigrescens_, _A. oreganus_, _and A. Trowbridgii_.
[31] Von Martens. _Cambarus cubensis._ Archiv. für Naturgeschichte, xxxviii.
All the crayfishes of the northern hemisphere belong to the _Potamobiidæ_, and no members of this family are known to exist south of the equator. The crayfishes of the southern hemisphere, in fact, all belong to the division of the _Parastacidæ_, and in respect of the number and variety of forms and the size which they reach, the head-quarters of the _Parastacidæ_ is the continent of Australia. Some of the Australian crayfishes (fig. 76) attain a foot or more in length, and are as large as full-sized lobsters. The genus _Engæus_ of Tasmania comprises small crayfish which, like some of the _Cambari_, live habitually on land, in burrows which they excavate in the soil.
New Zealand has a peculiar genus of crayfishes, _Paranephrops_, a species of which is found in the Fiji Islands, but none are known to occur elsewhere in Polynesia.
Two kinds of crayfish have been obtained in southern Brazil, and have been described by Dr. v. Martens,[32] as _A. pilimanus_ and _A. brasiliensis_. I have shown that they belong to a peculiar genus, _Parastacus_. The former was procured at Porto Alegre, which is situated in 30° S. Latitude, close to the mouth of the Jacuhy, at the north end of the great Laguna do Patos, which { 308} communicates by a narrow passage with the sea; and also at Sta. Cruz in the upper basin of the Rio Pardo, an affluent of the Jacuhy, “by digging it out of holes in the ground.” The latter (_P. brasiliensis_, fig. 64) was obtained at Porto Alegre, and further inland, in the region of the primitive forest at Rodersburg, in shallow streams.
[32] Südbrasilische Süss- und Brackwasser Crustaceen, nach den Sammlungen des Dr. Reinh. Hensel. Archiv. für Naturgeschichte, XXXV. 1869.
[Illustration: FIG. 76.—Australian Crayfish (1/3 nat. size).[33]]
[33] The nomenclature of the Australian crayfishes requires thorough revision. I therefore, for the present, assign no name to this crayfish. It is probably identical with the _A. nobilis_ of Dana and the _A. armatus_ of Von Martens.