158 Gastrulation and Embryo Formation in Amia Calva 
THe PRONEPHRIC Duct. 
The pronephric duct is preceded by a solid rod of cells which arises 
through a proliferation of the cells of the somatopleuric portion of the 
mesoderm, but before the appearance of a well defined ceelom. We do 
not agree with the observations of Felix and Biihler, 04, who state that it 
arises as an evagination of the somatopleure. The further study does 
not come within the scope of the present paper. 
SYSTEMATIC POSITION oF: AMTIA. 
Dean concludes his second paper, 96, on Amia with the statement that 
“at the base of a gradational series stands Lepidosteus, near it and in 
some ways even below it is Acipenser; next is Amia; next, and very 
closely related, is Amiurus; and, finally, are the many remaining forms 
of teleosts.” 
Previous studies by the senior author on Amia and Lepidosteus, the 
present study of Amia, together with the unpublished work on Ameiurus 
by the junior author, all indicate that such an arrangement, based upon 
early developmental characters, is not only premature but incorrect. 
The only conclusion which can be reached at the present time is that 
the evidence from cecology, anatomy, histology, embryology, is so frag- 
mentary that it affords no secure basis for assigning the various ganoids 
their respective places within the group, nor the group its position in 
the vertebrate phylum. 
BIBLIOGRAPHY. 
DEAN, BASHFORD.—The Early Development of Amia. Quart. Jour. Micr. Sc., 
Vol. XXXVIII, 1896, pp. 413-444. 
DEAN, Basurorp.—On the larval development of Amia calva. Zool. Jahrb. 
Abt. f. Syst., Bd IX, 1896, pp. 639-672. 
EYCLESHYMER, ALBERT C.—Notes on Celloidin Technique. Am. Nat., XXVI, 
1892, pp. 354-358. 
EYCLESHYMER, ALBERT C.—The Cleavage of the Egg of Lepidosteus osseus. 
Anat. Anz., Bd. XVI, 1899, pp. 529-536. 
EYCLESHYMER, ALBERT C.—The Early Development of Lepidosteus osseus. 
Univ. of Chicago Decennial Publications, Chicago, 1903. 
FELIX AND BiuLter—Die Entwickelung der Harn und Geschlechtsorgane. 
Handbuch d. vergl. u. exper. Entwickelung d. Wirbeltiere. O. Hert- 
wiged. Jena, 1904, Lief. XVIII, p. 135. 
Kerr, J. GranwAmM.—The Development of Lepidosiren paradoxa. Part II. 
Quart. Jour. Micr. Se., Vol. XLV, 1901, pp. 1-40. 
Kuprrer, C.—Studien zur vergl. Entwickelungsgeschichte des Kopfes der Kra- 
nioten. Heft I. Die Entwickelung des Kopfes von Acipenser Sturios 
an Medianschnitten untersucht. Miinchen, 1893, pp. 1-95. 
