542 TELEOSTEL CHAP. 
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. 8. 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 thiscountry. 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 Regan, who has himself 
endeavoured to settle some important questions of classification.’ 
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. 
, : 
9. Anacanthini. 10. Acanthopterygii. 8. Percesoces. 
7. Catosteomi. 5. Haplomi. 6. Heteromi. 8 
"o 
[ees ; f4. Apodes. = 
(3. Symbranchii. 
1. Malacopterygii- 2. Ostariophysi. 
—dl 
Ganoidei Holostei. 
' 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. 
