The Ganoids 1 1 



urged that any characters that have not been or cannot be directly 

 confirmed are problematical in the case of all other groups 

 (e.g., mammals), and it can only be replied that the coordina- 

 tion of parts has been so invariably verified that all probabili- 

 ties are in favor of similar coordination in any given case. 



" (2) There is doubtless considerable difference in the num- 

 ber of valves of the bulbus arteriosus among the various Ganoids, 

 and even among the species of a single family (e.g., Lepido- 

 steidaz), but the character of Ganoids lies not in the number, 

 more or less, but in the greater number and relations (in con- 

 tradistinction to the opposite pair of the Teleosts) in conjunc- 

 tion with the development of a bulbus arteriosus. In no other 

 forms of Teleostomes have similar relations and structures 

 been yet demonstrated. 



" (3) The failure of the spiral intestinal valve has already 

 been conceded, and no great stress has ever been laid on the 

 character. 



" (4) The chiasma of the optic nerves is so common to all 

 the known Ganoids, and has not been found in those forms 

 (e.g., Arapaima, Osteoglossum, and Clupeiform types) agreeing 

 with typical physostome Teleosts in the skeleton, heart, etc., 

 but which at the same time simulate most certain Ganoids 

 (e.g., Amid) in form. 



"Therefore, in view of the evidence hitherto obtained, the 

 arguments against the validity of title, to natural association, 

 of the Ganoids, have to meet the positive evidence of the co- 

 ordinations noted; the value of such characteristics and co- 

 ordinations can only be affected or destroyed by the demon- 

 stration that in all other respects there is (i) very close agreement 

 of certain of the constituents of the subclass with other forms, 

 and (2) inversely proportionate dissimilarity of those forms 

 from any (not all) other of the Ganoids, and consequently evi- 

 dence ubi plurima nitent against the taxonomic value of the 

 characters employed for distinction. 



"And it is true that there is a greater superficial resemblance 

 between the Hyoganoids (Lepisosteus, Am-ia, etc.) and ordinary 

 physostome Teleosts than between the former and the other 

 orders of Ganoids, but it is equally true that they agree in other 

 respects than in the brain and heart with the more generalized 



