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TRANSACTIONS OF SECTION D. 1069 
duct of the other bladder before entering the gullet. The pylorus also is remark- 
ably contracted. But the most striking and altogether curious arrangements are 
seen on the ventral wall of the abdomen. The intestine passes forward the whole 
length of the abdominal cavity to the vent, and on its under side is a long renal 
duct as wide as itself, and opening immediately behind the vent; while, opening 
into this duct close to its outlet, are the ducts of the two ovaries, which lie one 
on each side, their morphologically anterior extremities placed posteriorly, as if in 
process of development these organs had been pulled round from their proper sub- 
vertebral position until completely inverted. 
9. On the Spiracle of Fishes in its relation to the Head, as developed 
in the Higher Vertebrates, By Professor CLELAND, M.D., F.B.S. 
A very extraordinary mistake can be shown to be prevalent among embryo- 
logists, to the effect that the spiracle corresponds with the tympanum and external 
auditory meatus in the higher vertebrates. ‘This is not the case. The spiracle is 
pre-oral; the tympanum is post-oral. The apparent sequence of the spiracle with 
the branchial clefts occurs, as Balfour described it, in the embryo of the dog-fish ; 
but for all that, and although it has rudimentary external gills attached to its 
margins in the embryo, it is in front of the mandibular arch and above the maxil- 
lary lobe. Between the middle and lateral frontal processes is the nostril ; between 
the lateral frontal process and the mandible is the space into the upper part of 
which the eyeball projects, and from which the lachrymal duct is developed ; while 
between the first and second visceral lobes is the external ear; and it is highly 
probable that the upper part of the first branchial cleft is homologous with the 
clefts in front of and behind the lateral frontal process. Thus a certain amount of 
homology would exist between the spiracle of fishes and the lachrymal duct. 
10. On the Tail of Myxine glutinosa. By Professor Creanp, M.D., F.R.S. 
The dorsal and anal fins of Myavzne are continuous at the tail. They consist of 
numerous rays, which, when the integument is removed, are seen to be of fibrous 
structure imbedded in a thin membrane. But the inferior rays of the tail differ 
from the superior, in that the hindermost of them are supported by a triangular 
plate of cartilage about half an inch long, lying beneath the chorda dorsalis, and 
continued into about twenty-four longer or shorter processes. In front of them, at 
the anterior inferior angle of the triangle, is a smali bifurcated process, ending in 
two slight dilatations, which support the hindermost pair of mucous glands, The 
a plate is of a variety of cellular cartilage allied to the structure of the 
chorda. 
11. On the Nucleus in the Frog’s Ovum. By Grorce Tun, M.D. 
The paper describes conditions of the nucleus as observed in ova of rana tem- 
poraria, between the stages of division into four segments, and that of the end of 
segmentation when the ovum has assumed a moniliform or mulberry appearance. 
The appearances described were those observed when sections of ova hardened in 
bichromate of potash had been stained by picro-carmine. They refer exclusively 
to changes which carmine-staining shows takes place in certain unformed con- 
stituents of the nucleus. In the paper the nuclear network is left out of con- 
sideration, the methods of preparation not having brought it satisfactorily under 
observation. 
The conditions observed might be classified as follows: Ist. A tablet nucleus,* 
in which the distinctive carmine-staining was found associated with an unformed 
substance which infiltrates the yolk substance in certain parts of the segments. 
1 A literal translation of Téfelchen, the word used by Goethe. It is more appro- 
priate than such terms as ‘ yolk granules,’ ke. 
