140 JOHN BEARD. 
to our knowledge of the ancestry of Mammalia. It is mainly 
concerned with the description of rudiments of these branchial 
sense organs of the facial, glossopharyngeal, and vagus in 
Mammalia, viz. cow and sheep embryos. These rudiments 
are only found in certain stages and disappear later. When 
they still exist the corresponding ganglia of these cranial 
nerves, viz. the ganglia of facial, glossopharyngeal, and vagus, 
are fused with the skin, indeed, the conditions seem to be 
much the same as in Elasmobranchii. That the ganglia are 
wholly or partly derived from the skin in Mammalia Prof. 
Froriep hesitates to decide. It is somewhat remarkable that 
Prof. Froriep should have failed to find rudiments of such 
sense organs in connection with the Gasserian and ciliary gan- 
glia, and I cannot help expressing a firm conviction that such 
rudiments exist at some stage or other in Mammalian deve- 
lopment. This conviction rests on a twofold basis, an 
a priori one that in Elasmobranchii the sense organs of the 
ciliary and Gasserian ganglia are very well developed, and 
secondly, on the discovery, of which I hope soon to give a full 
account, that such rudiments occur, and are very ob- 
vious in embryo chicks. They are in the chick especially 
obvious in the cases of the ciliary aud trigeminal segments, 
but they also occur in the segments of the facial, glossopharyn- 
geal, and vagus. 
Of course here, as in Mammalia, they disappear after the 
fish stage has been passed through, but when they attain the 
maximum of their development one could almost fancy in 
studying them that it was an Elasmobranch embryo which was 
under examination. The state of affairs in both cases being 
so alike that one can only marvel that these rudiments have 
hitherto escaped notice in the chick. So much for the present. 
Tur Nose anp Ear as BRANCHIAL SENSE ORGANS. 
In the preceding pages abundant evidence has, I think, been 
adduced to show that the nose and ear are specialised branchial 
sense organs. Whether they ever had gill-clefts in connection 
with them is a point which, from the evidence at present at 
