- 5 - 



lacking ( Pander ichthvs ) . In the latter case, n. profundus possibly entered the nasal cavity 

 together with n. olfactorius, as Kulczycki noted for one of the forms of Porolep i s . 



Kulczycki considers that P orolep i s and Eusthenopteron have an identical arrangement of the 

 following nerves: n. opthalmicus profundus, n. max i liar i s, r. palatinus VII, r. buccalis VII 

 (fig. 4) and accompanying blood vessels. Thomson partly supports him in this. Thus, according 

 to Jarvik, the lateral parts of the snout in Osteolep i formes are supplied chiefly 



-p. 1362 — 



by r. max i liar i s V 

 The latter conside 

 V term i nates in an 

 lateral 1 i ne and c 

 orbital-rostral pa 

 stretches ahead fa 

 buccal i s later i s V 

 (fig. 4: 4, max pi 

 r. buccal i s later i 

 off small branches 

 the other hand, i t 

 across the orbital 

 of the infra-orbit 

 nerves passed aero 

 i n Eusthenopteron . 

 insufficient in hi 



, but in Por 



rs that Jarv 



orb i t . Mea 



orrespond ing 



ssage (trunc 



rther than i 



n Porole 



us buc) cani 



s passes for 



to the ante 



is d i v i ded 



-rostral pas 



al ca nal ( f i 



ss the derma 



I nf orma t i o 



op in ion 



ile, 

 ccal i : 

 inf rai 

 erres 

 , the 



ot be exc 



4: 3, 



ones 



bout 



n. profundus, which causes doubt on the part of Thomson, 

 fluenced here only by modern Urodela in which r. maxillaris 

 n some aquatic, tailed amphibians, where a system of a 



lateralis VII was retained, the latter passes into an 

 rbitales) together with r. maxillaris V and this mixed trunk 

 rial amphibians. And as far as traces can be found of 

 possibility of the presence in them even of r. maxillaris V 

 luded. Further, in agreement with Jarvik, in Eusthenopteron 

 he top of the snout laterally to the internal nares giving 

 s of the infra-orbital sensory canal. In Porolep i s , on 

 rai branches in the orbit and only one of them goes forward 

 ally from the internal nares supplying the forward part 

 r. buc). According to Thomson, in Ec tosteorhach i s the 

 ather than between these bones and the nasal capsule as 

 he arrangement of r. buccalis lateralis in Rhipidistia is 



R. palatinus VII in Eusthenopteron passes across the antero-lateral part of the vomer and 



passing it divides into three branches. In Porolep i s the nerve passes across the mediai part of 



the vomer and does not divide at this juncture. Thomson observed an analogous picture in 

 Ec tosteorhach i s . 



Jarvik affirms that traces of fusion of a pala to-quadrate complex and ethmoid are present in 

 Eusthenopteron and absent in Porolep i s . A contradictory opinion is held by Kulczycki who points 

 to the traces of a synchondral ic articulation between processus apicalis palat o-quadra turn and the 

 olfactory tract of the sphenethmoid in Porolep i s . It is possible that the merging of the palato- 

 quadrate complex with the ethmoid was characteristic of all Rhipidistia. In any case, the groove 

 for the pala to-quadra turn, which is noi covered by the periosteal bone, is present also on the 

 ethmoid of Ec tosteorhach i s . Pander icht hys and Platecephal ichthys . In connection with this, the 

 observations on the development of the endocranium of tailed amphibians (Hynob'idae) put forth 

 by N. S. Lebedkina ( 1 9^3 ) are interesting. They showed that in the larvae there is a close con- 

 nection of the palatal arch with the ethmoid. 



e of the differences between Osteolep if orn 

 henoid and the vomers. In Eust enopteron (fig 

 the ethmoidal tract to the prenasal area of t 

 plate and a long, posterior branch are met a 

 the openings of the i n t er-vomer i ne canal (in 

 ossa apicalis with the posterior part of th 

 wide and barely reaches to the ethmoidal tr 

 separated and lack a vertical plate of the 

 ion of Ec tosteorhach i s (Romer, 1 93 7 ) » * ne P 

 nsisting ot a base and a shagreen plate res 

 Eus thenodo n also has a similar formation ( 

 g the formation of the parasphenoid should 

 of both its parts. The width of the inter 

 the taxonomy of Rhipidistia in particular 

 Osteolep i do i de i and Holopt ych i i de i (Vorot 

 with the lenath of the 



and the Porolep 

 . 5) 'he parasp 

 he endocran i um; 

 head along the 

 tei — vomerine pi 

 oral cavity. I 

 t; the vomers w 

 ter-vomerine ca 

 aspheno id of Rh 

 ng on it. The 



rvik, 1937)- 1 

 v i ousl y lead to 

 bitai septum, w 

 a d i st ingu ish i 

 va, 1362)! The 



formes 

 heno i d 



the 

 suture 

 t, Iv. 

 n 



thout 

 nal. 



idist is 

 para- 



exam- 

 h i ch has 



--p. I363- 



anterior palatal recess (fossa apicalis, cavum i nt ernasale). The length of the shagreen plate 

 indicates various stages of evolutionary development, according to the opinion of Thomson. In 

 particular, the gradual transition from the stage of Eusthenopteron to that of Po rolep i s can be 



