206 Du. R. \v. sHUFELUT ON [Apr. 1, 



Just at tbib point 1 will pass from the consideration of those 

 organs that are entirely contained either within the hud}- or mouth- 

 cavities and record next a few brief notes upon some external 

 structures, such, for instance, as the poison-glands and their ducts \ 



Yll. The Poison-glands. (Plate XVI. fig. 4.) 



J. G. Fischer (-44) has presented us with a fair drawing of the 

 venom-organs oi Ileloderma hurridum as they occur upon either side of 

 the lower jaw. Of the ducts, of which there are four in the specimeu 

 I dissected, they passed, at a short distance aj)art, from the mesial 

 aspect of tlie middle of the gland upwards each to its opening on 



* Before parting compaay, however, with our researches upon the organs 

 contained in the ccelom and the cavity of the thorax, I would Uke to say a 

 word or two more in i-elereuce to the observations I have made concerning the 

 system of hepatic, cystic, and jiancreatio ducts ; and, secondly, as to the descrip- 

 tion recorded of the thyroid gland of lieloderma. In the case of the first- 

 mcutioned structures I desire to repeat the statement that my opinion 

 •about them is not final, as I should very much like to see additional material 

 and fully re-iuvesiigate structures that seem to be so notably different from the 

 more usual arrangement of these ducts in other vertebrate forms. To be sure 

 I devoted several hours to the careful e.xamination of the ducts in question, 

 and, as far as the circumstances would admit, I was satisfied iu my own mind 

 as to the peculiarities they presented; but that part of the vascular system of 

 tlie specimen undergoing dissection was not injected, and this may have given 

 opportunity tor error. Notwithstanding the cautionary words I here give, both my 

 deseri];ition of these parts and my d)'awiiigs of them may be absolutely correct ; 

 and if they be, why so much tlie better foi' the writer and his reputation. Speaking 

 of these hepatic ducts I see that Professor Hoflmaun found some interesting 

 arrangement of them in Alligators and Crocodiles (see Bronn's ' Thier-Eeichs,' 

 Rent. Bd. vi. o3 & 1)4 Lief., 1882), and, according to liim, the distribution of 

 the ducts varies for diffcnnt sprcii't< of Alligators, as sliown by the drawings in 

 the work quoted (Taf. C). It must be evident, however, from what I have said 

 upon a former page of this memoir, and fi-oui what Beddard found in a species 

 of Vi(raHU6 with regard to its bihary ducts, that fui-tiier investigation into theae 

 structures in Lizai-ds will well repay tlie laboui-s of the morpliologist. 



As to the thyroid gland in HcJodefum, and the description I have recorded 



in reference to it, I would say that I am aware of the position occupied by this 



structure iu other Lizards, as in LuarUi it occui-s as twosejiarate lobes opposite 



each other on the sides of the trachea some little distance abo\e the base of the 



heart. I e.vamined « ith no little care the oi-gan I have described as the thyroid 



iu our present subject : it was firm and flexible, and under a lens of moderate 



power had all of the appearances tjiat characterize glandular tissue. Be it 



noted, too, that the pericardial sac does not normally extend anteriorly beyond 



the base of the heart, nor connect vWlh any othei- sac overlying the origin of 



the great vessels that I am at ))resent aware of. Still, a small rujjture had 



taken place in one of the thin auricles of my specimen and some blood had 



escaped into the pericardial sac. and thi.s, stained with its own colouring-matter 



and hardened with the alcohol, had, I must confess, some little resemblance to 



tlie structure I have described as the thyroid; but it may have been a resem- 



blance and nothing more. The parts were all particularly sound and perfect 



otherwise ; furthermore, after carefully dissecting u]i both sides oi' the trachea, I 



utterly failed to find in my specimen any such thing as a thyroid in tlie locality 



wherein it occurs in Lacerfa. Again, it may have been some pathological 



growth, out an exauiinalion of a few recentl^ killed lleloderms would soon 



clear uj) all such doubtful points, and 1 sincerely trust that some day this will 



be done. 



