378 
encysted in the black bass and yellow perch, 
and adult in the mouth and throat of the 
great blue heron, gave me an opportunity 
to examine this form. It appears to be 
specifically identical with the one described 
by MacCallum in the Journal of Morphology 
(vol. xv, p. 697, 1899), as C. heterostomum, 
and by Braun (Zool. Jhrb. abt. f. System, 14, 
p. 1, 1900), as C. marginatum. There are, 
however, a number of points in which my 
material differs from the account given by 
MacCallum. The cuticle is armed with 
spines, they are very numerous, acutely 
tapering, run obliquely backward and are 
located wholly within the cuticle, barely 
projecting beyond its outer boundary in a 
few places. There is a single genital open- 
ing leading into a common chamber into 
which the uterus opens from in front and 
the cirrhus sack from behind. A pharynx 
as described by MacCallum is wanting. 
The oral sucker, as surmised by Braun, is 
directly followed by a characteristic cesoph- 
agus, lined with cuticle and supplied with 
usual longitudinal and circular muscle 
fibers—and surrounded by glandular cells, 
apparently forming the customary cesoph- 
ageal gland. Circular muscle fibers are 
demonstrated in the intestines as well as 
longitudinal ones in iron hematoxalin 
stained sections. The oviduct opens into 
the uterus near its anterior end and not 
posteriorly as indicated by MacCallum. 
Glandular cells abound in the area directly 
in front of the ventral sucker, but ducts 
from them to the oral disk, as described by 
Braun, have not as yet been recognized in 
my material. 
Note on the Marginal Sense Organs of Cotylo- 
gaster occidentalis: W. S. NicKERSON. 
(Paper accompanied by demonstrations.) 
Members of the Trematode family Aspi- 
dobothridz, with but one known exception 
(Stichocotyle) , have a series of organs in the 
margin of the large multilocular sucker 
SCIENCE. 
[N. S. Vou. XIII. No. 323. 
which have been generally regarded as sen- 
sory structures. These organs in C. occi- 
dentalis appear to be both sensory and 
glandular in function. Each is made up of 
a bulb-shaped body measuring about 38 x 
27 », which communicates with the exte- 
rior by means of a narrow tortuous duct 
whose outer portion is lined by cuticula 
continuous with that covering the body. 
The duct arises from the distal end of the 
bulb, making first a sharp bend downward 
beside the bulb for about one-half the 
length of the latter, then making a second 
sharp turn toward the surface, where it 
opens directly over the bulb. The appear- 
ance of the contents of the bulb varies 
from finely granular to coarsely vesicu- 
lar, corresponding probably with different 
phases of activity of the glandular proto- 
plasm. Nuclei (except those of nerve 
cells) are not distinguishable in the bulb. 
The duct is capable of eversion so that the 
interior of the bulb may be protruded 
through the opening. A bundle of deli- 
cate nerve fibers enters the bulb at its basal 
end. The chief interest in the organ cen- 
ters, however, in a cluster of bipolar cells 
lying upon the side of the bulb toward 
which the ductturns. These are undoubt- 
edly sensory cells, and their peripheral proc- 
esses are probably distributed upon the 
walls of the duct, although the exact place 
and method of their termination could not 
be made out in the specimens studied. The 
presence of the bipolar sensory cells estab- 
lishes the sensory character of the organs 
which hitherto has been a matter of con- 
jecture. 
The Changes in the Facial Cartilaginous Skeleton 
of the Flatfishes, Pseudoplewronectes Ameri- 
canus (a dextral fish) and Bothus maculatus 
(sinistral): &. R. WiLiraMs. 
In specimens of P. americanus about 
34 mm. long whose eyes are still perfectly 
normal jin position the two supra-orbital 
