xxvi 



It will be noticed that all these objections (save in the case of the intes 

 tinal spiral valve) are hypothetical and vague. The failure of the intes 

 tinal spiral valve, as a diagnostic character, has long been conceded, and 

 in this case only have the forms that prove the failure been referred to ; in 

 the other cases, where it would be especially desirable to have indicated 

 the actual types falsifying the universality or exclusiveness of the charac 

 ters, they have not been referred to, and the objections must be met as if 

 they were not known to exist. 



(1) The characters in question are, in the sense used, problematical, in 

 asmuch as no examination can be made of the soft parts of extinct forms, 

 but with equal force may it be urged that any characters that have not 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 co-ordination 

 of parts has been so invariably verified that all probabilities are in favor 

 of similar co-ordination in any given case. 



(2) There is doubtless considerable difference in the number of valves 

 of the bulbus arteriosus among the various Ganoids, and even among the 

 species of a single family (e. g., Lepidosteidse), but the character of Ga 

 noids lies not in the number, more or less, but in the greater number and 

 relations (in contradistinction to the opposite pair 1 of the Teleosts) in con 

 junction 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 common to all the known Ga 

 noids, and has not been found in those forms (e. g., Arapaima, Osteoglos- 

 sum, and Clupeiform types) agreeing with typical physostome Teleosts in 

 the skeleton, heart, etc., but which at the same simulate most certain Ga 

 noids (e. g., Amid) in form. 



benden Ganoiden vorfinden ; man braucht sich nur [2] der grossen Differemen in der 

 Zahl der Aortenstiel-Klappen bei Lepisosteus und Amia zu erinuern, oder [3] des Um- 

 standes, dass eine Spiralklappe im Darmcanale unter den lebenden Fischen nicht 

 bios bei Ganoiden, sondern aucli bei Selachiern und mehreren Knochenfischen (Gat- 

 tungen der sogenannten intermediaren Clupeiden-Gruppen) und nicht bios im Diinn- 

 darme, sondern auch in andern Abtheilungen des Verdauungsrohres sich vorfindet, 

 und dass auch [4] die Chiasmabildung keineswegs einen verlasslichen Unterschied 

 der Ganoiden abgibt. Kner, op. cit., pp. 522-523. 



This paragraph is the only one that squarely meets the question of the applica 

 bility of the fundamental characters of the Ganoids, as given by Miiller. It need only 

 be added that the ideas respecting probability of pertinence must be a reflection from 

 the deductions resulting from a more or less thorough study of the known elements. 

 The question as to the value of the chiasma is certainly disposed of in a very sum 

 mary manner, but not in an equally satisfactory one. 



1 &quot;The sunfish (Orthayoriscus) has four such valves.&quot; Owen, Anat. Vert., I. 474. 



