1891.] Embryology 287 
recent acquisitions from new organs in the female; while the state of 
things in the marsupial strengthens the hypothesis. In the lowest 
Australian marsupial there are no glands in the male, but a scrotal 
pouch in the place of the female inguinal glands. In Monotremes 
there are male glands, but no scrotum as yet formed. 
The discovery of remnants of such mammary glands in the area 
into which the testes descend would increase the value of the 
hypothesis. Such are present in all groups of mammals, conspicuous 
in apes, and even found in man, in embryos. 
The ‘‘ area scroti’’ are warty, circumscribed regions of the scrotum, 
one on each side, in which peculiarities of skin glands, hairs, and 
especially of skin muscle, form strong contrasts to the rest.of the 
scrotal skin. 
These ‘‘area scroti’’ are the externally visible outlines of these 
primitive mammary organs that gave rise to the descent of the testes. 
On the Urinogenital System of the Crocodile and Turtle.’ 
—1. There is an undoubted trace of a pronephros in embryos of both, 
which soon degenerates. 2. A very large glomerulus hanging into the 
body-cavity on either side. Often the nephrostomes of the pro- 
nephros are close to its sides. 3. A segmental arrangement could not 
be made out for pronephros or glomerulus; no very young embryos 
were examined. 4. The boundary between, pronephros and meso- 
nephros could not be made out, and it was not possible to count the 
number of nephrostomes belonging to either. 5. The origin of the 
pronephros—whether from ectoderm or mesoderm—cou!d not be de- 
termined. 6. Nephrostomes of the mesonephros often become par- 
tially or wholly separated from the body-cavity by a growth upward 
of the lower lip of the funnel, which surrounds the glomerulus above it. 
7- The Milllerian duct is formed entirely independently of the seg- 
mental duct, by a félding of the peritoneal ephithelium anteriorly, 
constricting off the proximal end of the duct, which then grows’ back- 
to the cloaca as a solid rod of cells, which soon acquires a lumen. 
—J. L. KELLOGG. E . 
The Development of Cyanea arctica.—Since the publication 
by Louis Agassiz of the third volume of his ‘‘ Contributions to the 
Natural History of the United States’? no observations have been 
recorded upon the development of Cyanea arctica. During the month 
of May of the past summer this Medusa was exceedingly abundant in 
ineyard Sound and the adjacent waters, and on my arrival at the 
“R. Weidersheim. Arch. f. Mik, Anat., Band 36, Heft 3, 1890. - 
Am. Nat.—March.—7. ee 
