19^ DR. R. W. SHUFELDT ON [Apr. 1, 



(4) a few interlacing ducts, joined by one or two (?) hepatic ducts 

 occurring on the surface of the gall-l)ladder or just near it. 



In figure 2, of Plate XVI., I present a drawing of the liver (and 

 other parts associated) of Heloderma, and although in that drawing 

 the parts are of their normal sizes and lengths they are pulled rather 

 downwards and forwards in order to show them off better. 



The Spleen. — This peculiar organ is of a bright red colour in the 

 living Heloderma, and, as in so many Lizards, is freely swung in the 

 fold of the peritoneum known as the mesogaster. In form it is sub- 

 ovoid, being rounded at one end and rather pointed at the other, and 

 lies about a centimetre from the concave curvature of the stomach. 

 It measures in length, in a large specimen of the Heloderma, VA 

 centimetre, and has a width of about 8 millimetres. A large 

 vein leads from it which joins the portal vein, while it is supplied 

 with arterial blood by the splenic artery, which is a branch of the 

 dorsal aortic artery. In its position it lies upon a crossing of a 

 number of the vessels borne by the mesogaster, but in so far as I 

 can see they seem to have no other special connection with this 

 organ. 



Very little seems to have been written about the spleen in Lizards. 

 Dr. Giintber l.as said that the " spleen and pancreas are very elon- 

 gate and narrow " in Hatteria ^ As referring to Reptiles, the word 

 " s()leen " does not even occur in the General Index (vol. iii.) of 

 Sir Richard Owen's ' Anatomy of Vertebrata,' and I fail to find any- 

 thing definite about that organ in the Rejitilia in the same work. 

 In liana the spleen is placed near the anterior commencement of 

 the rectum. Turner, who is pleased to notice the great value of work 

 done in " comparative anatomy," has not a word to say upon the com- 

 liarative morphology of the spleen in bis article upon the general sub- 

 ject of Anatomy, and in that article confines what he has to say upon 

 the organ under consideration to a few words having reference to the 

 anatomy of the spleen in a single type representing but a single family 

 of the Vertebrata (Homo)'-. It is hardly to be expected that we 

 shall ever possess a very complete knowledge of the physiology of 

 this organ so long as we remain so ignorant of its comparative mor- 

 phology. In this Lizard it has simply the appearance of a large, 

 isolated lymphatic gland, and the remark of Huxley that "The 

 spleen is substantially a lymphatic gland," may still bespeak the 

 summation of our knowledge upon that point ^. 



The Alimentary Canal. — In describing this we shall for the present 

 pass by the tongue and certain other structures that pertain to the 

 mouth-parts, and present what we have to say about them further 

 along. 



The (Esophagus consists of a straight tube extending from the 

 buccal cavity to a point opposite the apex of the heart. In its pba- 



^ Giinther, " Contributions to the Anatomy of Hatteria (i? hychocephalus, 

 Owen)," Phil. Trans, pt. ii. 1867, p. 28. 



^ Turnpr, William, Article "Anatomy": Encyclopaedia Britannica, 9th 

 edition, vol. i. (sec pp. 819 and 907). 



'•* Huxlej-, T. H., ' The Anatomy of Vertebrated Animals,' p. 91. 



