206 DR. R. \V. SHUFKLDT ON i^V'^- 1» 



Just at this ]>oiiit 1 will pass ironi the consideration of those 

 organs that are entirely contained either within the body- or uiouth- 

 cavities and record next a few brief notes ujion 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 Heloderma korridwn as they occur upon either side of 

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

 I dissected, they passed, at a short distance apart, from the mesial 

 aspect of the middle of the gland upwards each to its opening ou 



^ Before parting compauy, however, with our researches upon the organs 

 contained in the coeloin and the cavity of the thorax, I would like to say a 

 V ord or two more in reference to the observations I have made concerniug the 

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

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

 mentioned structures I de.sire 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-invesiigate structures that seem to be so notably different from the 

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

 1 devoted several hours to the careful examination of the ducts in cpiestion, 

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

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

 the specimen undergoing dissection was not iiijected, and this may have given 

 opportunity for error. Notwithstanding tlie cautionary words 1 here give, both my 

 descrijition of these jiarts and my drawings of them may be absolutely correct ; 

 and if they be, why so much the better for the writer and his reputation. Speaking 

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

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

 Kept. Bd. vi. oo & .j4 Lief., 1882), and, according to hiiu, the distribution of 

 the ducts varies for different species of Alligators, as shown by the drawings in 

 the work quoted (Taf. C"). It must be evident, liowever, i'rom what I have said 

 upon a former page of this memoir, and from what Beddard found in a species 

 of Vurauus with regard to its biliary ducts, that iiu-tiier investigation into these 

 structures in Lizai-ds will well repay the labours of the morphologist. 



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

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

 structure in other Lizards, as in Liweiiu it occurs as two separate lobes opposite 

 each other ou the sides of the trachea some little distance above the base of the 

 heart. I examined with no little caie the oi-gan 1 have described as the thyroid 

 in our present subject ,; it was firm and flexible, and under a lens of moderate 

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

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

 the base of the heart, nor connect with any othei- sac fiverlying the oi-igiu of 

 the great vessels that 1 am at present aware of. Still, a small rupture had 

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

 escaped into the pericardial sac, and this, stained with its own colom-ing-matter 

 and hardened with the alcohol, had, 1 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 ]3articularly sound and perfect 

 otherwise ; furthermore, after carefully dissecting uji both sides of the trachea, 1 

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

 wherein it occurs in Laccrfa. Again, it may have been S(ime pathological 

 growth, out an examination of a few recenllv killed ]iclodcrms would soon 

 clear up all such doubtliil points, and 1 sincerely trust that some day this will 

 be done. 



