^Jouml^oS^^^ PROGRESS OF MICROSCOPICAL SCIENCE. 215 
is so different from its condition for vision, that he considered the 
failure to photograph lines of such exceeding delicacy no proof that 
the lines could not have been seen, and more than that, that tbe failure 
of one operator to photograph with a certain instrument is not to be 
accepted as a proof that another observer with another instrument and 
other manipulations failed to see these lines. Mr. E. C. Greenleaf 
showed a specimen of Amjphijpleura pellucida, mounted dry, on which he 
claimed to show the markings. As this has been one of the most diffi- 
cult of the diatoms to resolve, and perhaps the one about the resolving of 
which there has been the most dispute, Mr. Greenleaf proposed leaving 
the matter open for further examination and discussion. Dr. Eufus 
King Browne, of New York, being present, spoke of the difficulty of per- 
fectly resolving the markings on this form ; he considered the markings 
as granules or tubercles, which appear as lines or punda, according to 
the light thrown upon them, and that the markings v/ere not as fine or 
close as claimed by microscopists." This observation so thoroughly 
confirms the results obtained by our President (the Kev. J. B. Eeade, 
F.E.S.) and Mr. Wenham, that it deserves attention at the present 
time. 
A Peculiar Minute Thread-worm infesting the Brain of the Snake- 
bird (Plotus anhinga). — Dr. Jeffries Wyman, the well-known American 
physiologist, has described and figured a minute parasite of the Nema- 
toid group, which he has found in great multitudes in the brain of 
the Snake-bird of East Florida. The parasites were in all cases 
found coiled up on the back of the cerebellum, just behind the cere- 
bral lobes ; in one case there were so many of them that they made 
" a deep indentation of the cerebellum." The female is readily distin- 
guished by being much larger than the male, measures 65 milli- 
metres in length, and when fully distended with eggs has a diameter 
of 0*5 millimetre. The mouth is terminal, without lips or papillse, 
the intestine passes in a straight direction to the opposite end of the 
body, and if it opens at all does so at the point of it, though the open- 
ing itself was not distinctly seen. Several loops of the oviduct are 
easily observed through the integuments, and one much larger than 
the rest can be seen at the hinder part of the body. The genital 
pore was not found, but is probably in the middle portion of the body, 
as near the two ends only loops of the oviduct are seen, and these 
nowhere connected with the walls. The male is only about one-half 
the linear dimensions of the female, and the hinder portion of the 
body is always more closely coiled. The intestine has the same 
arrangement as in the female. Near the hinder end of the body, and 
on the concave side of the last half-coil, is a papilla from which in 
one case we saw the male organ protruded, having the form of a 
slightly recurved spine. The base of this was buried beneath the 
surface, and in close relation to the end of the spermatic tube. In 
almost every instance the oviducts were largely distended with ova in 
different stages of development, and with hatched young. The eggs 
are of an oval form, their long diameter being about 0*02 millimetre. 
Those least advanced contained simply granules, and others had the 
embryo roughly sketched by the arrangement of the whole mass of 
