30 



MR. E. LEONARD GILL ON THE PERMIAN 



at a right angle just above the ai'ea of attachment of the scapulo- 

 coracoid cartilage. This latter cartilage has left a distinct trace 

 of its form in two or three of the specimens (text-fig. 9). Many 

 specimens show the pointed lower ends of the tvvo cleithra 

 meeting (or slightly displaced from their normal contact) in the 

 midv^entral line, and prove the entire absence of an infra- 

 clavicle. 



The skeleton of the pectoral fin of J. . varians is shown in text- 

 fig. 9. The radials are about eight in number. They appear as 

 a single series, though slight cups shown in their outer ends may 

 have lodged minute distal cartilages. The first fin fulcrum, 

 vphich is large, seems always to be based directly on the scapular 

 cartilage in series with the radials. There is no sign of the 



Text-figure 9. 



A. Skeleton of left pectoral fin of Acentrophorus varians. Dotted lines show the 



approximate shape of the scapirlo-coracoid cartilage and of three postaxial 

 radials which have only been seen as impressions. From a specimen in the 

 Kirkby Collection and one in the Sunderland Museum. 



B. Part of preaxial edge of pectoral fin of Acentrophorus gJafliyrns, showing the 



long, slender fulcra. Prom a specimen in the Kirkbj' Collection, Hancock 

 Museum. Both figures about four times natural size. 



presence of a metapterygium. The dermal rays are about twice 

 as numerous as the radials, and where it happens that two 

 adjacent rays are supported by one radial, the bases of these rays 

 are noticeably inclined together. The two first (pre-axial) rays 

 are unbranched, and the three last (post-axial) are both un- 

 branched and unjointed. The remaining rays are all forked 

 twice in the distal thii-d of their length. 



The pelvic fins ai-e very short-based, and are remarkable exter- 

 nally for the great length attained by one of the fulcra (text- 

 fig. 10, B). Specimens in v/hich the inner surface of the scales 

 is exposed not infrequently show the supporting bone of the 



