Bennet M. Allen ~ 93 
the sex-cords have disappeared leaving only the funnel-cords, the other, 
that the sex-cords which primitively existed in this region have taken 
on the character and function of funnel-cords. It is difficult to decide 
this question. I can merely say that the latter assumption seems the 
more probable one, because often two or more rete-cords can be seen in 
a single transverse section to arise from more than one point of the 
peritoneum covering the rete ridge. In fact the strongest and most nu- 
merous rete-cords arise from the portion of it that lies nearest the mesen- 
tery. This question might be solved with certainty by a study of the 
conditions in the Monotremes or even in other less primitive groups of 
mammals. 
LITERATURE CITED. 
AICHEL, OTTO, oo.—Vergleichende Entwickelungsgeschichte und Stammes- 
geschichte der Nebennieren. Arch. f. mikr. Anat., Bd. LVI, 1900. 
ALLEN, B. M., 04.—The Embryonic Development of the Ovary and Testis of 
the Mammals. American Journal of Anat., Vol. III, 1904. 
Batrour, F. M., 78.—A Monograph of the development of the Elasmobranch 
Fishes. Works of F. M. Balfour, 1878. 
Braun, M., 77.—Das Urogenitalsystem der einheimischen Reptilien. Arb. 
Zool.-zoot. Institut, Wiirzburg, Bd. IV, 1877. 
HorrMann, C. K., 89.—Zur Entwickelungsgeschichte der Urogenitalorgane bei 
den Reptilien. Zeitschr. f. wiss. Zool., Bd. XLVIII, 1889. 
92.—Sur le dévéloppement de lV’appareil. uro-génital des oiseaux. Verh. 
d. Koninklyke Akademie v. Wetenschappen te Amsterdam. Sectie 2, 
Deel I, No. 4, 1892. 
JANOSIK, J., 85.—Histologisch embryologische Untersuchungen tiber das Uro- 
genitalsystem. Sitz. Ber. Akad. Wien, 3 Abth., Bd. XCI, 1885. 
go.—Bemerkungen tber die Entwickelung des Genital Systems. Sitz. 
Ber. Akad. Wien, 3. Abth., Bd. XCIX, 1890. 
LAULANIE, F., 86.—Sur le mode d’évolution et la valeur de l’épithelium germi- 
natif dans le testicule embryonnaire du Poulet. C. R. Soc. de 
Biologie, T. 3, 1886. ; 
MIHALKOvics, V., 85.—Untersuchungen tiber die Entwickelung des Harn- und 
Geschlechtsapparates der Amnioten. Inter. Monatschr. f. Anat. Hist., 
isxol, Aig alkegslay 
MOLLER, F. v., 99.—Ueber das Urogenitalsystem einiger Schildkroten. Zeitschr. 
f. wiss. Zool., Bd. LXV, 1899. 
The most plausible theory is that the rete-region of the mammals has not 
been directly derived from a condition like that in Chrysemys; but that the 
genital ridges of both have been derived from a type in which the anlage of 
the sex-cords was co-extensive with that of the funnel-cords. 
To be more exact then, the rete-region of the mammals corresponds to the 
anterior end of the sex-gland of the turtle plus the modified region of funnel- 
cords anterior to it. ; 
