1907.] AFRICAN SILURID FISHES. 1063 



surely cannot liappen in this instance, and the Clariince therefore 

 teach us that a head protected by a bony buckler may gradually 

 transform into one which is entirely devoid of such protection, a 

 process of evolution which I am convinced has taken place in 

 many and diverse groups of lower Vertebrates. 



I have recently adduced this example of the Clariince in 

 endeavouring to refute Prof, von Mehely's inacceptable theory 

 that, in the group of Lacerta murcdis, the more feebly ossified 

 skulls represent the more primitive types. In a recent reply to 

 my criticisms*, my distinguished colleague of Budapest more 

 ■clearly expresses his general views on evolution. As he thinks 

 that the lizards with toothless palate are the oldest (" dass die 

 Stammform noch keine Gaumenzahne besass," p. 474), that the 

 pterygoid teeth were acquired by the later forms, and as he 

 ■endorses the extraordinary Jaeckelian hypothesis of fishes having 

 been derived from land Vertebrates {Prototetrapoda), I fear further 

 discussion with him on such matters would be mere waste of 

 time. Nor can I feel sympathy for innovations in classification 

 which are expressed by such barbarous terms as Neolacertce and 

 Archceolacertce. 



OLARIIN^. 



Synopsis of the Genera. 



A. Dorsal fin sin<?le, formed entirely of articulated rays. 



1. Eye with a free border ; pectoral and ventral fins well developed. 



Sides of head protected by bony shields 1. Clarias Gvou. 



■Sides of head naked, only the postorbital shield 



being present 2. Allahenclielt/s Blgr. 



2. Eye without fi-ee border; sides of head naked. 

 Postorbital shield present ; pectoral fins well de- 

 veloped, ventrals small 3. Clariallahes Blgr. 



Postorbital shield absent ; pectoral and ventral fins 



very small 4. Gymnallab es Gth.!:. 



Postorbital shield absent ; pectoral fins rudimentarj' 



or absent, ventrals absent o. Cliannallahes G:t\i.r. 



B. Dorsal fin divided into two, the posterior portion adipose. 



Sides of head protected by bony shields; adipose 



dorsal fin large and supported by bonj' ra3's (the 



produced neural spines) 6. SeterobraneJius Geofir. 



Sides of head naked, only the postorbital shield being 



present ; adipose dorsal fin small 7. Dinotopterus Blgr. 



1. Olarias. 



Gronovius, Zoophvl. p. 100(1781); Giinther, Cat. Fishes, v. 

 p. 248 (1864); Boulenger, Poiss. Bass. Congo, p. 248 (1901), and 

 Fishes of the Nile, p. 278 (1907). 



Macropteronotus, part., Lacepede, Hist. Poiss. v. p. 84 (1803). 



South-Eastern Asia, Syria, and Africa. 32 species are known 

 from the latter part of the world. 



* Ann. Mus. Hung. v. 1907, p. 469. 



