1907.] OF CERTAIN SPECIES OP SQUAMATA. 55 



of the hyoid arch. The ligament thvis avoids the fii"st branchial 

 under which it lies. It is not surprising to find that Trachydo- 

 saurus, so closely allied to Tiliqua, also possesses this second 

 branchial arch. As in the genera mentioned, the arch is only 

 represented by its upper part, the epibranchial, as Parker termed 

 the equivalent cartilage in Lacerta. Finally, I have to record 

 that the bar of cartilage is also found in GerrJionotus, a genus 

 of whose anatomy I offer some further notes below. In the 

 present state of our knowledge it is not possible to state whether 

 or not this occurrence does or does not bear upon the affinities of 

 Gerrlionotus. The cartilage was not so easy to find in this small 

 Lizard, where it is slender and delicate, but can be detected 

 by gently moving in various directions the muscles in its vicinity ; 

 the stiff' ends of the cartilage thus become apparent. 



A second feature in the anatomy of Zonurus to which I desire 

 to draw attention is the total absence of the gubernaculum fixing 

 the apex of the ventricle to the walls of the pericardium. This 

 ligamentoiis band or thread (it varies in importance in different 

 genera) is so visual among the Lacertilia as to be characteristic of 

 that order of Reptiles, as it is, indeed, of others. I have already 

 pointed out that the gubernaculum cordis is not to be found in 

 the heart of Varamos niloticits and some other species*. It is 

 interesting to notice that this absence of the gubernaculum which 

 is universal in the higher Vertebrates ( Aves and Mammalia), as 

 well as generally in the Ophidia t, is sporadically developed among 

 the Lacertilia. It should also be mentioned that this condition 

 of the heart was found in two examples of Zonurus giganteus (the 

 third was not examined ad hoc)% ; it is therefore probably charac- 

 teristic of the species if not of the genus. 



The liver of this Lizard is unusual in its form. The right lobe 

 is prolonged in the usual way over the vena cava. But the left 

 lobe, instead of being but slightly divided at the entry of the 

 anterior abdominal vein, is deeply bifid thereat §. The whole 

 organ is thus markedly trifid posteriorly and is not unsuggestive, 

 in appearance, of the mammalian liver. 



The pancreas displays one noteworthy character. Its general 

 form is like that of the majority of Lacertilia. The organ embraces 

 the stomach, being found on both sides of it ; the splenic lobe is 

 fairly stout and reaches the spleen, and there is a process of the 

 gland extending towards the liver. The peculiarity of the pancreas 

 of this Lizard is that diffuse thin i-amifying tags of pancreatic 

 tissue lie in the mesentery on either side of the splenic lobe of the 

 gland with which they are connected. This tendency towards a 

 diffuse irregularly shaped thin pancreas is obviously to be com- 

 pared with the conditions obtaining in the Ohelonia. 



* P. Z. S. 1906, vol. ii. p. 617 footnote. 



f Pei-liaps universallj^ also. In any case the occasional ligament tying the apex 

 of the heart to the pericardium is rather different (see P. Z. S. 1904, vol. ii. p. 107). 



X I have since found the same absence of the ligament in another example. 



§ I am not quite certain that it is not the right lobe which is thus bifid. It is a 

 point difficult to settle. 



