542 



TELEOSTEI 



the present day, about 11,500 belong to this order. The classi- 

 fication of such an array of forms is, of course, a matter of great 

 difficulty, and gives scope for much difference of opinion among 

 those who have attempted to grapple with the subject. It is 

 now recognised that the study of the skeleton affords the safest 

 guide to a natural arrangement of the families and higher 

 divisions. Much has been done in this line by Cope, Gill, 

 Sagemehl, A. S. Woodward, and Jordan and his pupils ; but the 

 osteology of many important types still remains unknown. For 

 some years a large number of skeletons have been prepared in 

 the British Museum with the object of settling open questions, 

 and this material has enabled me to draw up a scheme of classi- 

 fication which, whatever its defects, and however provisional, I feel 

 sure is on the whole an improvement on those hitherto proposed, 

 and especially on that generally in use in this country. The latter 

 was, to a great extent, based on physiological principles ; the present 

 aims at being phylogenetic. In its preparation I have derived 

 great benefit from the labours of the authors quoted above, but 

 have endeavoured in every instance to verify their statements on 

 a larger osteological material than appears to have been available 

 to them. I have also had the advantage of the criticism, on many 

 points, of my young colleague, Mr. C. Tate Eegan, who has himself 

 endeavoured to settle some important questions of classification. 1 

 The Order Teleostei is divided into thirteen sub-orders, the 

 probable relations of which are expressed in the following 

 diagram : 



11. Opisthomi. 13. Plectognathi. 12. Pediculati. 



I ! ! 



9. Anacanthini. 10. Acanthopterygii. 8. Percesoces. 



7. Catosteomi. 5. Haplomi. 6. Heteromi. 



1. Malacopterygii 



/4. Apodes. 



{3. Symbranchii. 



2. Ostariophysi. 



Ganoidei Holostei. 



1 A synopsis of the classification followed in this work has been published in the 

 Annals and Magazine of Natural History (7), xiii. 1904, p. 161. Some corrections 

 have been introduced, chiefly due to the investigations of Dr. W. G. Ridewood. 



