657 



this respect from the bones of the Eel, in which such corpuscles are 

 abundant* ; in 1853 I made known -f that the bones of Leptocephalus 

 and Helmichthys contain no trace of bone-corpuscles ; a year later, 

 Mettenheimer showed that the same was true of the bones of Tetra- 

 gonurus Cuvieri'l ; and in 1855 Quekett mentions, in the second 

 volume of the ' Histological Catalogue of the College of Surgeons of 

 England,' fishes belonging to eighteen genera, in the bones of which 

 he had not succeeded in finding bone -corpuscles viz. Fogmarus 

 islandicus, Lophius piscatorius, Gadus morrhua, Ephippus, Sparus, 

 Trigla cuculus, Belone vulgaris, Pleuronectes platessa, Trachinus 

 vipera, Orthagoriscus mola, Exoccetus, Scarus, Esox, Sphyrcena 

 barracuda, Tetrapturus, Zeus faber, Percafluviatilis, Gobiofluvia- 

 tilis. But, notwithstanding these most valuable observations, little 

 or no progress seems to have been made in the more general treat- 

 ment of this matter, as is best shown by the 'Comparative Histology' 

 of Leydig (1857), in which (p. 157) the Leptocephalidce, Tetrago- 

 nurus t and Orthagoriscus are the only cases mentioned, in which the 

 radiated bone-corpuscles are wanting. 



On commencing a series of more extended investigations into the 

 minute structure of fish-bones, in October last, I found that the 

 genera which possess real osseous tissue are rather scarce, whilst, 

 on the other hand, I fell in with a great many types in which the 

 bones contained no trace of lacunae. A.nd as this fact not only ap- 

 peared to me of interest with regard to the development of the bones 

 of fishes, but also promised to become of great value in systematic 

 zoology, and in the determination of fossil remains, I devoted my 

 whole time to this question. Now that I have investigated more 

 than 200 species belonging to nearly all tribes of osseous fishes, and 

 mounted about 500 microscopic preparations of their hard structures, 

 I hope to be able to treat this question more comprehensively than 

 has been possible hitherto, and in such a way as to lead to some 

 general conclusions. 



In giving the results of my observations, I begin with an enumera- 

 tion of the fishes which belong to the one, and those which belong 

 to the other type. 



* Phil. Trans. 1851, p. 693. f Zeitschr. f. wiss. Zool. iv. p. 361. 



J Anat.-histol. Untersuch. ii. d. Tetragonurus Cuvieri, in den Abh. d. Senken- 

 berg. Gesellschaft, i. p. 241, 



