Prof. J. van der Hoeven on the Genus Menobranchus. 363 



XL VI. — Notes on the Genus Menobranchus and its Natural 

 Affinities. By J. van der Hoeven*. 



One of the most important improvements in the natural distri- 

 bution of Reptiles is undoubtedly the separation, effected by 

 Merrem and F. S. Leuckart in 1820 and 1821, of that class into 

 two groups, named by the former Pholidota and Batrachia. 

 (Tentamen systematis Amphibiorum, auctore Blasio Merrem, 

 Marburgi, 1820.) The Batrachians have the skin naked, while 

 the Pholidota have the body covered with scales or enveloped in 

 two bucklers (Chelonia). Leuckart, by introducing the appel- 

 lation Dipnoa for the Batrachians, has seized and made use of a 

 more essential character, viz. the double respiration, the presence 

 of branchiae at an early stage, or the existence of branchiae perma- 

 nently with lungsf. We owe to M. Fitzinger the name Monopnoa, 

 corresponding to that proposed by Leuckart, and serving to dis- 

 tinguish the other great division or that of the Pholidota of 

 Merrem J. 



The researches of various authors have contributed more and 

 more to confirm this primary division. The celebrated physio- 

 logist Miiller has, above all, by drawing attention to certain 

 anatomical characters which had not been sufficiently regarded, 

 demonstrated the perfectly natural character of these groups §. 



There is, in fact, so great a difference between the reptiles of 

 these two divisions that Merrem considered them two distinct 

 classes — an opinion shared by De Blainville. It does not enter 

 into our present purpose to discuss this view ; we would, how- 

 ever, remark that the doctrine advanced by a modern author, 

 according to which the Dipnoa should be united with the Fishes, 

 seems to us an exaggeration, and opposed to a truly natural 

 classification. 



Among the reptiles with double respiration we must place 



* Translated from a separate impression, communicated by the author, 

 from the 'Archives Neerlandaises, tome i. (1866), by Arthur O'Shaugh- 

 nessy. 



t Oken's 'Isis,' 1821, Litterarischer Anzeiger, 257-265 : "Einiges iiber 

 die fischartigen Amphibien." 



X Neue Classification der Reptilien, von L. J. Fitzinger : Wien, 1826. 



§ " Beytrage zur Anatomic und Naturgeschichte der Amphibien," 

 Zeitschrift fiir Physiologic, herausgegeben von F. Tiedemann, G. R. Tre- 

 viranus, und L. C. Treviranus, iv. Bd., 2 (1832), p. 190 &c. This remark- 

 able work dates at the commencement of the author's scientific career ; he 

 then occupied the chair of Physiology at the University of Bonn. Amongst 

 the anatomical characters of the Dipnoa must be cancelled that of the 

 simple auricle formerly attributed ' to the heart of Batrachians. (Seethe 

 author's supplementary note, pp. 274-2/5.) It is, however, especially 

 worthy of remark, as a twofold embryological character, that both amnios 

 and allantois are here wanting, while they are present in all other reptiles, 

 as well as in birds and mammals. 



25* 



