May 23, 1913] 



SCIENCE 



807 



Pander." Sauripterus Hall, a supposed Rhizo- 

 dont from the Upper Devonian of Pennsyl- 

 vania has a pectoral girdle and forepaddle 

 which distantly approach Stegocephalian con- 

 ditions" and so also, but in less degree, has 

 Eusthenopteron.'' 



Par more definite evidence of the supposed 

 relationship of the Stegocephali with the Pale- 

 ozoic Crossopterygii has recently been ad- 

 duced by D. M. S. Watson," of Manchester, in 

 describing some of the large Stegocephalia of 

 the Coal Measures preserved in the Newcastle 

 Museum. He finds that the skulls of 

 the Carboniferous Labyrinthdonts, " Lox- 

 omma" and Pteroplax reveal striking re- 

 semblances to the Carboniferous Crossoptery- 

 gian MegalicMhys: 



The Basisphenoid of MegalicMhys has some- 

 times carotid foramina just as in Loxomma. It 

 has small but distinct basi-pterygoid processes 

 ■which are, however, not provided with articulating 

 surfaces but with sutural ones. The long para- 

 sphenoid extends forward to the premaxillas as it 

 may do in Pteroplax. Its lateral borders are in 

 contact with the Pterygoids, to which they afford 

 support, and the bone is connected with the roof 

 of the skuU by a fused ethmoid. 



The pre-vomer is identical with that of "Lox- 

 omma" in the majority of its attachments, carries 

 one large tusk and a pit for the replacing tooth. 

 It meets its fellow of the opposite side and forms 

 the front of the posterior naris; it is doubtful, 

 however, if it meets the palatopterygoid. 



The Palatopterygoid of MegalicMhys is exceed- 

 ingly like the palatine and pterygoid of Pteroplax. 

 They have similar relations to the basisphenoid, 

 parasphenoid and maxilla. There is the same row 

 of small teeth parallel to those of the maxilla with 



" ' ' Ueber die Saurodipterinen, Dendrodonten, 

 Glyptolepiden und Cheirolepiden des Devonischen 

 Systems," 1860, pis. 1-3. 



"Cf. Gregory, Science, N. S., Vol. XXXIII. 

 1911, p. 509. A figure of this forelimb by Hussa 

 kof has recently been published by Dr. Bertram 

 Smith in the Journal of Morphology, Vol. 23, No, 

 3, 1912, p. 544. 



"Cf. Patten, "The Evolution of the Verte 

 brates," 1912, p. 391. 



" ' ' The Larger Coal Measure Amphibia, ' ' Mem. 

 and Proc. Manchester Literary and Fhilos. Soc.. 

 Vol. LVII., Part I., No. 1, 1912, pp. 1-14, 1 pi. 



larger teeth inside them, and the pterygoid is cov- 

 ered with the same shagreen of fine teeth. 



Examination of these primitive and extremely 

 well-preserved skulls seems to show that the ordi- 

 nary idea of autostylism of the Tetrapoda is 

 incorrect in postulating a connection between the 

 pterygo-quadrate cartilage and the otic region. It 

 is, I think, quite certain that there never was such 

 a connection in primitive forms, except through 

 the dermal bones of the temporal region. The 

 lower attachment with the basisphenoid I have 

 just shown to exist in Crossopterygians, which 

 are hence ' ' amphistylic, " in a different way to 

 Notidanus. 



The large teeth on the palatine, with in- 

 folded bases, exhibit a curious type of tooth 

 replacement which is 



very characteristic of the Stegocephalia, and is 

 unknown elsewhere except in the Crossopterygian 

 fish, where it occurs in a very typical form in the 

 vomerine tusks of MegalicMhys, and no doubt in 

 many other genera, and in Lepidosteus. This oc- 

 currence seems to me a strong additional reason 

 for regarding the Tetrapoda as derived from this 

 group of fish." 



The lower jaw of "Loxomma" likewise ap- 

 proaches the Crossopterygian type in the fact 

 that the splenial is " entirely a bone of the 

 outer side of the jaw as is the first infraden- 

 tary of the Crossopterygian mandible." 



Watson's observations also have important 

 bearing on the relations of the Permian rep- 

 tilia. These have been distinguished from 

 contemporary Stegocephalians chiefly by the 

 single basi-occipital condyle and by the large 

 pterygoids, which leave only a small inter- 

 pterygoid vacuity, divided by a narrow para- 

 sphenoid. Watson has shown that these and 

 other " reptilian " characters are fully ex- 

 hibited in "Loxomma" Pteroplax, Anthraco- 

 saurus and other Carboniferous Stegocepha- 

 lians, that these characters they share also with 

 MegalicMhys and that no palate with large 

 vacuities like that of Eryops or Capitosaurus 

 has ever been found in Carboniferous rocks. 

 He therefore concludes that " the reptilia were 

 separated off very early in the history of the 

 Stegocephalia, preserving features which were 



" Hid., p. 5. 



