XIII. 1-2 



(357) 



2. Terrestrial Palaeozoic Amphibia. Embolomeri and Rhachitomi 



We possess more complete information about the slightly later 

 forms, the Embolomeri, such as *Eogyrinus, from the Lower Carboni- 

 ferous (Fig. 21 1). These were long-bodied animals, rather newt-like, 

 and their small limbs cannot have made very effective progress on 

 land. They probably lived mostly in the water, eating fish. The 



Fig. 208. Skull of Ichthyostega. (From Westoll, after Save-Soderbergh.) 



d. dentary; en. external nostril; ept. ectopterygoid ; jr. frontal; in. internal nostril; ina. 

 internasal; /. jugal; la. lachrymal; mx. maxilla; na. nasal; pa. parietal; pal. palatine; pm. 

 premaxilla; pn. postnarial; po. postorbital; poj. postfrontal; pop. preopercular; ppa. post- 

 parietal; prj. prefrontal; ps. parasphenoid ; pt. pterygoid; q. quadrate; qj. quadratojugal ; 

 san. sur-angular; sq. squamosal; sut. supratemporal ; /. tabular; v. vomer. 



pectoral girdle was still joined to the skull by a process of the tabular 

 bone, as in fishes. The pelvic girdle did not form a full articulation 

 with the sacral vertebrae but was apparently attached only by liga- 

 ments. 



The structure of the vertebrae has given rise to much controversy. 

 In the earliest amphibia we find three elements, a more dorsal neuro- 

 pophysis and a centrum composed of two parts, pleurocentrum and 

 hypocentrum, the latter associated with a ventral arch and rib. These 

 elements can be identified in the vertebrae of crossopterygians but it 

 is still not clear what relationship, if any, they have to the two pairs of 

 vertebral 'arches' alleged to be present in elasmobranchs (see Williams, 



J 959)- 



