104 ASTACIDjE. 



Georgia, the best explored portion of the country, suggests how much 

 may be found in the adjacent States. The Middle States arc in pari i 

 better explored, but without doubt they will furnish many new species 

 or show a wider distribution of the known species, as is stated in our 

 catalogue. 



It would be very interesting to ascertain whether the extensive table- 

 lands between the Sierra Nevada of California and the Rocky Moun- 

 tains, as well as the great American desert, possess species of the genus 

 Astacus or of the genus Cambarus or not. As yet nothing is known 

 about these regions. 



Perhaps under these circumstances a detailed exposition of the geo- 

 graphical distribution of the North Amei'ican Astacidce would be prema- 

 ture and incorrect, but some facts are too striking and too apparent to 

 be overlooked, even at this stage of our knowledge. 



The first and chief point ascertained as yet is the strict limitation 

 of the genera Astacus and Cambarus, which completely exclude each 

 other. In the parts west of the Sierra Nevada, and perhaps of the 

 Rocky Mountains, lives the genus Astacus, in all the eastern parts the 

 genus Cambarus. At present no exception is known. Tins fact is all 

 the more interesting, as the only species known from the eastern parts 

 of Asia. Astacus Dauricus Pallas, which is probably identical with Astacus 

 leptorMnas Fisher, from the Amur River, seems to be a group interme- 

 diate between the European and North American species of Astacus, and 

 more nearly related to the species of the latter country. 



Our knowledge of the geographical distribution of the North Amer- 

 ican species of Astacus is as yet too limited for us to say anything more 

 respecting them. 



The second fact, which seems to be ascertained, is that the genus 

 Cambarus is confined to the other parts of North America and perhaps 

 to the Antilles. I have not seen the species described by Erichson and 

 de Saussure from Cuba, but it doubtless belongs to the genus Cambarus. 

 The asserted presence of the genus Cambarus in South America is to be 

 discredited, unless further and more trustworthy evidence be produced 

 in its favor. C. Ckiknsis, mentioned by Erichson as a species of Cam- 

 barus, was never seen by him, and seems from the description to be 

 more nearly related to Cheraps, or perhaps to represent some distinct 

 genus. I have seen one and only one specimen of Astacidai from Brazil, 

 — if there be no error as to the habit, which was apparently the case 

 with some Astacus JhwiatiUs communicated to me as Brazilian species, — 

 a male in a very bad state of preservation, and evidently nearly re- 

 lated to C < 'lii/i n-six. As the specimen is dry and very old, it is impos- 

 sible to ascertain whether it have gills or not on the fifth pair of leg . 



The C. Bartmm, figured and described as perhaps from Brazil by Mr. 

 Dana in his excellent work, is certainly not identical with the C. JJnr- 





