28 



PROCKEDlXnS OF THE 



Tlie real links in question, so far :i8 we know tliein, are ainono- 

 the extinct paiUlle-finnecl lislies (fig. 1) wliieli Pander and Huxley 

 re«;:ir(Ied as l)elon<,Mng to tlio same group as the existing J'oh/jitems 

 and CaluitioichtJii/s. 1'lie lishes ot this group (Crossopterygii *) 

 liave indeed changed greatly in progress oF time, and the further 

 hack they are traced the more nearly do tliey approach the early 

 amphihians, which appeared very little later than tiiemselves. If 

 the existing Polifjitents and Calamoichthys alone were known, the 

 relationship would he scarcely evident; for they are tvpically 

 " mature " or even " senile " forms of the group, with an elongated 

 body, modilied cheek-plates, completed vertebrie, and highly 

 specialised tins. The primitive Devonian genera, however, exliibit 

 resemblances which are unmistakable and have long been 



i'jg. 1. 



An Upper Devoniau Crossopterygian, Holopti/chius floiiivr/i, restored by 

 Pr. B. H. Traqiiair, about, one-eighth nat. size. 



noticed t. The enlarged conical tusks on the vomerine bones, and 

 in fact the whole appearance and arrangement of the teeth, 

 resemble those of tlie typical Stegocephala. Tlie peculiar 

 structure of the teeth, with a more or less complex folding of the 

 walls of dentine, is also nearly the same in the two groups. The 

 complexity of the mandible in the early Crossopterygian fishes is 

 much like that in the Stegocephala, and the symmetrically 

 arranged dermal ])lates of the skull and cheelvs correspond very 

 closely. Some oi' the Crossopterygians, such as OsteoJepis J and 

 Diplopterus. exhibit a pineal foramen, exactly as in all the 

 Stegocephala. Some of them, such as certain Ehizodonts and 

 Coolacanths, also agree w'ith the Stegocephala in having sclerotic 

 plates round the eye. Finally, it is to be noted that the earliest 

 Stegocei)hala have the pterygoid bones extended and nearly as 

 large as those of the Crossopterygii §, the reduced pterygoids with 



* T. H. Huxley, Figs. & Descript. Brit. Organic Reniains. dec. x. (Mein. 

 Geol. Siirv. 1861), p. 24. 



t A. S. Woodward, 'Outlines of Vertebrate Palffiontologv ' (1898), p. 1*23, 

 fig. 81. 



X E. S. Goodrich, .Journ. Linn. Soc, Zool. vol. ^cxxiv. (1919). pp. 181-188. 



§ D. Einbleton & T. Attl)ey, Nat. Hist. Trans. Northunib. & Durham, toI.t. 

 (1877), p. -07, ]il. ii. (Loxomiua nllmaiivi), and j). .319, ))1. vii. {Anthmcosaurus 

 ri'ssc/li); D. M. S. Watson, Mem. & Proc. Manchester Lit. &. Tlul. Soc. 

 Tol. r>7 (1912), no. 1. 



