BRITISH FOSSILS. 



Decade IX. Plate VIII. 



MEGALURUS DAMONI. 



[Genus MEGALURUS. Agassiz. (Sub-ldngdom Vertebrata. Class Pisces. Order 

 Goniolepidoti. Family Sauroidei. Sub-family Sauroidei bomocerci. 2nd Group, tail 

 more or less rounded.) Caudal fin very large and rounded ; dorsal fin opposed to tlie 

 interspace between the ventral and anal fins ; bead large ; jaws furnished with large 

 conical teeth, intermixed with smaller ones. Vertebral centres ossified.] 



Megalurus Damoni, Sp. Nov. 



This remarkable genus is placed by Professor Agassiz in a small 

 group at the end of the Sauroid family, comprising in addition one 

 fossil genus Macrosemius, and the recent genera Lepidosteus and 

 Polyp)teTUS. The characters common to these four genera are the 

 upward tendency of the termination of the vertebral column, and 

 the rounded form of the caudal fin. In other respects they differ 

 widely from each other. M. Pictet, laying greater stress upon 

 the dermal peculiarities, has proposed a new order, " les ganoides 

 cycliferes," for the reception of the fossil ganoids having rounded, 

 imbricated scales. He divides this order into four families ; the 

 first comprises the recent Amia, and the fossil genera Notoeiis and 

 Gyclurus ; the second, "les Leptolepides,'' the genera Leptolepis, 

 Tharsis, Thrissops, Megalurus, Oligopleurus, and Coccolejns ; the 

 third and fourth, " les Celacanthes and les Holopty chides,''^ 

 embrace the Cselacanthoid family of Agassiz. Tliis is not the place 

 to discuss at length the validity of the proposed new arrangement. 

 The objections to it are manifold, and until some more satisfactory 

 solution of the admitted incongruities of the old system is pro- 

 pounded the lesser evil will be to abide by the latter, rather than in- 

 troduce new elements of discord of greater magnitude than those 

 complained of The ordinal titles proposed by M. Pictet involve 

 a contradiction, for he associates together as " Ganoides cycliferes 

 several genera, some having and some devoid of the true ganoid 

 character of the scales. Again, in his second order, les Ganoides 

 rhombiferes/' he includes Pachycormus and Caturiis, genera in 

 which the rhomboid form of scale becomes nearl}^ obsolete, and the 

 [IX. viii.] 9 I 



