1030 The American Naturalist. [November, 
crossed. The little fish is at this stage so largg that the double 
nature of the mouth involution may be seen without aid of a lens, 
The author is not committed as to whether the breaking through of 
the ventral region represents a pair of gill-clefts,—7.e., as to whether the 
Teleost (and vertebrate) mouth arises, as Dohrn supposed, from a ven- 
tral fusion of a pair of fused gill-clefts. 
‘Triple Fertilization in Egg of Domestic Fowl.—The infre- 
quency with which triple fertilization takes place in the same ovum, 
in birds or mammals, is in itself reason for presenting to the scientific 
student what appears to be a unique specimen illustrating this phe- 
nomenon, and upon which may also rest the basis of certain biological 
speculations. In view of this I have drawn the specimen (see Plate 
XXII.), shown for the first time, representing topographical features 
rather than histological detail. 
The literature at my disposal and such inquiries as it was possible for 
the writer to make from reliable sources failed to recall another 
recorded instance of triple fertilization occurring in domestic fowl. 
It is in this connection interesting to note that Hertwig, Fol, Pluger, 
and other observers of note are unanimous in the conclusion that 
‘“ polyspermy,’’ or more than one spermatazoa entering the ovum, is 
extremely rare, and, as a matter of fact, generally impossible ; and 
where it does occur in rare conditions, it indicates a pathological con- 
dition of the egg-cell, giving rise to the production of abnormalities. 
Here we have, in all probability, the entrance of three sperms into 
the ovum,—a condition indeed so rare as to excite more than ordinary 
interest in the mind of the naturalist. 
Iam indebted to Dr. J. C. Millman, formerly in the biological 
laboratory of the University of Wisconsin, for the generous spirit with 
which he brought to my notice and allowed me the pleasure of laying 
the specimen before the reader.—Dr. JosepH L. Hancock, Chicago, 
September 29th, 1891. i 

