and its Natural Affinities. 373 



a succession which T believe to be sufficiently natural, although, 

 strictly speaking, every arrangement in a single series is de- 

 fective. 



Fiuall}'^, since the anatomical materials respecting the genera 

 of North America are very much dispersed (being contained 

 partly in journals and memoirs of societies and academies not 

 always to be found in the very largest of public libraries), it 

 would be very desirable to have collected together all that has 

 been published upon these doubtful reptiles of America. There 

 would then remain another undertaking, viz. to arrange in a 

 systematic form all that we now know concerning the various 

 forms of this small group "^^ and this, though a work of com- 

 pilation, could be executed only by an able naturalist. 



The labours of Rusconi with reference to the Proteus are well 

 known ; but, as regards the other genera, the Cryptohranckus of 

 Japan is almost the only one of which we have any complete 

 anatomical details, viz. those which we obtain through the re- 

 searches of the three physicians of Rotterdam, published by the 

 Societe Hollandaise, and from the admirable work of one of the 

 greatest anatomists of our time, Professor Hyrtl of Vienna. 



It is to be lamented that there still reigns some confusion 

 throughout much of what has been published respecting these 

 doubtful reptiles, and even in works of well-merited celebrity. 

 It is stated in the 'Erpetologie generale' that I have figured 

 the nuchal fissure in the Cryptobranchus of Japanf, whereas the 

 entire plate, and consequently also the figure cited, refers to the 

 North-American species. The work of Dumeril and Bibron 

 having certainly a much more extended publicity than my 

 Dutch memoir J, I have thought it advisable not to neglect the 

 present occasion to remove this error, and the m.ore so since I 



by the great number of their vertebrae. Cuvier counted 86 vertebrae in 

 the Siren, 99 in Amphiuma tridactyla, and 112 in Amphiuma didactyla 

 (Mem. du Museum, xiv. p. 8). 



* Unless we suppose that the genus Proteus contains several species 

 (Fitzinger, " Ueber den Proteus anguineus der Autoren," Sitzungsberichte 

 der mathem.-naturw. Klasse der Kaiserl. Akad. der Wissenchaften, October 

 1850), the entire group numbers scarcely ten species. I know not what 

 to think of the eight species of Necturus which Rafinesque affirms to 

 exist in the United States (Journal de Physique, Ixxxviii. p. 418); but 

 they have not been noticed by those who have written about the fauna of 

 North America since his time. 



t " II n'y aurait done de difference que dans I'abseiice du trou coUaire 

 qtie M. van der Hoeven a figure pi. 2. fig. 8," &c. (ix. p. 164). 



X I regret extremely that Prof. Dumeril, the venerable veteran who 

 honoured me with his friendship, did not consult my " Fragments zoo- 

 logiques," in the third volume of the ' Memoires de la Socie'te de Stras- 

 bourg' (1840), where ray memoir on the Pscudosalamauder, the great 

 Japan reptile, is translated entire. 



