SÉANCE DU 24 AVRIL 1889 



219 



with the clavicle in its middle portion, and extends backwards for a 

 distance equalling half the length of the spine; and the bone is 

 evidently preserved as far upwards as its suturai connection with the 

 supra-clavicle, though unfortunately mutilated near the rigid lower 

 symphysis. 



)) Dorsal Spine, etc. — The dorsal spine, associated by Dixon 

 with « Silurus Egertoni », corresponds so closely in the character of 

 its ornamentation with the pectoral appendage already referred to, 

 that there can be little doubt as to the correctness of the corréla- 

 tion. » 



2. A. S. Woodward. Quoique les fossiles de Dixon ne puissent 

 évidemment pas appartenir (ainsi qu'il sera expliqué plus loin en 

 détail) au genre Silurus, et bien qu'on ait fait une seconde édition de 

 Geologv and Fossils of Sussex (1), on continua, partout, jusque très 

 récemment (2), à parler du « Silurus » Egertoni. C'est M. A. S. Wood- 

 ward, qui, le premier, rectifia cette erreur. 



Il commença par augmenter le matériel d'étude, comme cela résulte 

 des lignes suivantes (3). 



« Cranial bones. — But the most satisfactory materials for discus- 

 sion consist in a number of fragments of the cranium, which were long 

 ago labelled by sir Philip Egerton and Mr William Davies as pertai- 

 ning to the présent species, though no description of them seems to 

 have been hitherto published. Thèse bones are ornamented externally 

 in a very similar manner to the clavicular plate already noted, and 

 their size is such that they may well have belonged to the fishes indi- 

 cated by the detached fin-spines. The only élément, however, that is 

 capable of certain détermination is the supraoccipital bone — fortu- 

 nately one of the most characteristic bones in the Siluroid skull — 

 and of this four good examples are preserved » 



Après quoi, il procéda à la critique de la manière ci-après. 



« Systematic position. — From the foregoing facts, it is obvious, 

 that the Siluroid species under considération was characterized (i.) by 

 the présence of a strong dorsal fin-spine in addition to the pectorals ; 

 (ii.) by a large, ornamented dermal plate attached to the scapular arch; 

 and (iii.) by the ornamentation of the upper cranial bones, which are 

 evidently not covered with more than a very thin skin. In ail thèse 



(1) A. S. Woodward Siluroid Fishes, etc. p. 3o3. 



(2) J Phillips. Manual of Geology. Part II. R. Etheridge. Stratigraphical 

 Geology and Palœontology. i885. Londres, p. 643. 



(3) A. S. Woodward. Siluroid Fishes, etc., p. 3o5. 



