presence of traits characteristic only of amphibians, rather bear witness in favor of a monophylatic 

 origin of modern amphibians (Shmal ' gauzen, 1 959 ) * Special interest is created by the ascertainment 

 of the homology of "doubtful structures", i.e., structures casting doubt on the generality of their 

 origin among various forms of amphibians. Their number includes, in part, the lepospondylous type 

 of vertebrae and the structure of the limbs of Urodela. The wholly cylindrical vertebrae of 

 Lepospondyli are similar to the vertebrae of Urodela. As the studies of I. I. Shmal'gauzen ( 1959 » 

 1964) have shown, in the latter, the vertebrae are formed by the same elements as in other amphibians. 

 They could easily have 



-p. 1357" 



* 



issued from a rachitomous type basic for all tetrapods, 

 situation of Lepospondyli is without foundation. 



the representation of the isolated 



The difference in the embryonic development of ti.e limbs of the modern Urodela and Anura served 

 as one of the bases for their d i phylet icism. At one time Holmgren ( 1933 ) presented a diagram of the 

 limbs of the Urodela and Anura on the basis of embryolog i cal investigations and generalizations. The 

 first diagram was notable for the presence of the jointed skeletal axis testifying, as it were, to the 

 origin of the limbs of Urodela from biserial arch i pteryg ium of lungfishes or the Dipnoi. The basis for 

 the formation of such an axis was the presence of a skin formation between the first two digits in the 

 larvae of Hynobi us at early stages of development. This formation in the opinion of I. I. Shmal'gauzen 

 \i959) ' s coenogenet ic. This diagram does not correspond to the formation of the limbs of a single 

 representative of tetrapods including mature Urodela. The composition of the limbs of the latter is 

 very similar to that of the remaining tetrapods especially the labyri nthodonts, e.g., Eryop s and 

 Trematops (Shmal'gauzen, 1915)- The diagram given by Holmgren for Anura reflects the general structure 

 of a pentadactyl limb with the exception of mature Anura whose limbs are highly specialized. 



The diff 

 before Holmgre 

 citing these d 

 quotat ion from 

 Anura, on the 

 one another?" 

 restrial amphi 

 should we expl 

 limbs in these 

 results, that 

 an incorrect p 

 of the primary 

 however, that 

 conclusion tha 

 provide a basi 

 (Sewertzoff, 1 



the limbs of 

 ) as has been 

 the diphyleti 



therefore ac 

 loped phyloge 

 eld the idea 

 t ion on i tted 

 i lar i ty in th 

 usions furthe 



a preconceiv 

 y in the deve 

 e ancestors 

 ore probable 



development 



Urodela deve 



Urode 

 note 

 c i sn 

 cept 

 net i c 

 of th 

 y Ja 

 e pos 

 T 



ed op 

 lopme 

 f ter 

 expla 

 of el 

 loped 



la and Anu 



d by 



of a 



that 



ally 



e mo 



rvik 



i t io 



hey 



i n io 



nt 



rest 



nati 



)n o 

 lea 



frorr 



ra were examined even 

 k (1964). The latter, 

 ans, used a part ial 

 imbs of the reptiles 

 plete independence from 

 et i c ori g i n of ter- 

 ates: "But in what wayW 

 keletal elements of the "" 

 o such improbable 

 t they derived from 

 digits is an expression 

 ertebrates. We see, 



, and we have come to the 

 of autopodium does not 



1 form with a small radius" 



The conclusions of Jarvik produced critical response even from some paleo ichthyolog i sts. 

 (Vorob'eva, 1962; Kulczycki, I960; Romer, 1962; Thomson, 1962, 1964; Gross, 1964). As was shown b\ 

 the study of a series of lungfishes ( Porolep i s . Pander ichthys . Platycephalichthys . Ec tos teorhach i s 1 

 the characteristic types of snout in Porolep i formes and Osteolep i formes presented by Jarvik 

 argument for polyphylet ic i sm did not find confirmation in many points. It became clear tha 

 types of snout embraced far from all Rhipidistia. According to a series of traits, the two 

 overlap because of the presence of intermediate forms. In addition doubts were expressed a 

 viability of the interpretation of separate structures, and also of the possibility of thei 

 homologous with the structures of the ethmoid of modern amphibians. 



. .2 



Jarvik considers (Jarvik, 19*2) the character of the internasal wall one of the basi 

 of the osteolepif orm and porolepiform types of snout. In Eusthenopteron (fig. 2, l) the na 

 are close together and separated 



as a bas ic 

 t these 



types 

 bout the 

 r being 



c differences 

 sal cav i t ies 



-p. 1358- 



by a fine, continuous partition (septum nasi). In Porolep i s (fig. 2, 2) on the other hand, they are 

 widely separated, and between them is situated the ethmoidal section of the cranial cavity in front 

 of which lies the paired internasal pit (cavum internasals) , which, according to Jarvik, contains the 



'For the subsequent survey of the peculiarities of of formation of osteolep if orm and porolepiform types 

 of snout we have in mind this particular work of Jarvik and therefore no citations to it will be given^ 



