(9100 9 
XI.— Upon the Thyroid Glands in the Cetacea, with Observations on the Relations 
of the Thymus to the Thyroid in these and certain other Mammals. By W1Lu1AM 
Turner, M.B. (Lond.), Senior Demonstrator of Anatomy, University of Edin- 
burgh. 
(Read 2d April 1860.) 
In the writings of comparative anatomists, considerable difference of opinion is 
expressed respecting the position and relations of the thyroid gland in the Cetacea, 
and some authorities even have asserted that it does not exist in these Mammalia. 
JoHN Hunter states* that he has examined several porpoises, baleenze, and 
other cetacea, yet “ could not observe anything like a thyroid gland.” 
MEcKELft believed that he found, in a foetal porpoise (D. phocena), eight inches 
long, a thyroid gland. He describes it as half an inch broad, two lines thick 
and high, and of equal depth and thickness both on the middle and sides of the 
air-tube, in the same position as that in which the gland is found in other mam- 
mals. From this examination, however, of so young a foetus, he does not feel 
disposed to affirm that, contrary to the opinion of HunTrn, it exists in full grown 
cetacea. In a subsequent paper? he mentions incidentally, that in the dolphins 
the gland is formed of two quite separate lobes. Cuvrer§ states that he has 
found the gland very distinct in many dolphins and porpoises. In these animals 
it was divided into two parts, and suspended from the trachea opposite the upper 
border of the sternum, and some distance from the larynx. Carvus|| describes the 
gland in the dolphin and porpoise as consisting of two parts, entirely separate from 
each other. It is difficult to say, however, from the text, whether he is giving the 
result of his own observations, or simply adopting those of Cuvier. Dr Martyn 
repeats the statement that the cetacea do not possess a thyroid, and he ascribes 
the supposed absence of the voice in these animals to the want of this glandular 
structure. 
As I have had, during the last three years, opportunities of dissecting three 
porpoises, and as I have found in them appearances differing from those which I 
have quoted from the above authorities, I am induced to offer the following 
description of my observations. The animals were specimens of the common 
* On the Structure and Economy of Whales. Philosophical Transactions, 1787. 
+ Abhandlungen aus der Menschlichen und Vergleichenden Anatomie und Physiologie. Halle, 
1806. 
t Beytrage zur Vergleichenden Anatomie, 1811. 
§ Anatomie Comparée, vol. vill. 
|| Traité Elementaire d’ Anatomie Comparée, vol. ii. 
{ Proceedings of the Royal Society of London, 1857. 
VOL. XXII. PART IT. 4N 
