182 
If the state of affairs be as I have described it for Petromyzon, 
the Myxinoids present no difficulties; for, on the authority of WıE- 
DERSHEIM!), the conditions of the branchial apparatus of Myzine are 
derivable from those of Petromyzon. He writes: „Trotz dieser Diffe- 
renzen ist die merkwürdige Kiemenorganisation der Myxinoiden aus 
der der Petromyzonten abzuleiten. Es handelt sich um eine Weiter- 
entwickelung der bei den Petromyzonten schon angebahnten Verhält- 
nisse (Einwärtsrichtung der Kiemenblätter) d. h. um eine Verlegung 
des Respirationsapparates ins Innere des Darmes.“ 
From any existing Ganoids no-one would think of deriving the 
Marsipobranchii, the probabilities appear to be that the ancestors 
of the latter were among or allies of the earliest existing ancestors of 
the former. 
The interrelationships of the Ganoidei. 
Regarding existing Ganoidei themselves I also wish to say a 
few words. 
I do not believe that the facts of comparative anatomy, or of 
development, justify the present division into Chondrostean and Ho- 
lostean forms. The resemblance between the brains of Acipenser and 
Amia?) is so close as almost to amount to identity. The same also 
holds for a comparison between the brains of Lepidosteus and Amia. 
There are, it is true, some points of difference in the development of 
Acipenser and Lepidosteus — of which more presently — but the 
figures of Amia embryos, as recently given by ALLIS*), prove it to 
be completely Lepidosteoid. 
The condition of the brain and some other points in the compar- 
ative anatomy of Amia led me more than a year ago to the conclusion 
that Amia must be classed with the Lepidosteini. Aurıs’ valuable 
memoir confirmed this view in a most convincing manner. The suckers 
certain lateral sense organs gave rise to the organs of taste, but that they 
took mucous glands along with them to form the salivary glands, if this 
be so, the reason of the union of cause and effect between tasting and 
salivation becomes obvious. 
1) Wieversuermm, R., Lehrbuch der vergleichenden Anatomie der 
Wirbeltiere, 2 Auflage, 1886, p. 605. 
2) GoRoNoWITScH, N., op. cit. 
3) Aıııs, E. P., The anatomy and development of the lateral line 
system in Amia calva. Jour. of Morphol. Vol. II, 1889, p. 464, see 
especially Plates XXX—XXXII, 
