THE MARSIPOBRANCHII. 145 
extending that observation to the Sturgeon and perhaps to 
Ama (with a correction of Rathke’s original remarks* 
concerning the former of these two animals). While I 
gladly accept this definite contribution to knowledge, I 
fail to see that it necessarily implies the derivation of the 
genital system of the living Ganoids and Teleosteans from 
that of the Elasmobranchs, with loss of connection between 
the testis and kidney, as believed by Semon.t His 
observations necessitate the provisional relegation of the 
Ganoids to the opposite series to which I assigned them, 
and demand a reconsideration of my surmise “that the 
formation of the Mullerian duct must have preceded that 
of the vas deferens’’ (p. 556). Beyond these points, I 
remain adherent to the views expressed in my earlier 
communication. 
EXPLANATION OF THE PLATES. 
Puate VIII. 
Table indicating certain structural relationships of the 
living Ichthyopsida. (see p. 144). 
PLATE, LX; 
Figs. 1, 2, and 5, are intended to indicate the homologies 
of the labial, mandibular, and hyoid-arch systems of 
Petromyzon, Bdellostoma, and Callorhynchus, as deter- 
mined in the text. The obliquely-lined areas represent 
the labial and allied superficial cartilages; the stippled 
ones the parts of the mandibular and hyoid arches. 
* Schriften der Naturf. Gesellsch. Danzig. Bd. I, 1824. 
tcf. my former paper cited p. 555. 
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