72 MR. A. SANDERS ON THE [Jan. 6, 



the symphysis of the mandible, while the deeper fibres are inserted 

 into the outer edge of the tongue. The part of this organ to which 

 these fibres are attached is separated from the central portion by a 

 deep furrow ; this is the case on each side, so that this animal 

 appears to have three tongues— a central one broad, fleshy and blunt, 

 which is flanked by a pair, smaller and pointed. 



Hyoglossus (fig. 1, H.G.), slightly overlapped by the last, arises 

 from the distal extremity of the thyro-hyal ; the fibres pass obliquely 

 forward and inward, and partly join those of its fellow of the opposite 

 side by means of a raphe ; some of the other fibres are inserted into 

 the glosso-hyal, while the remainder pass into the lower side of the 

 central part of the tongue, in the substance of which they pass for- 

 ward to its anterior extremity. The two preceding muscles do not 

 appear to be represented in the Iguana*. 



Cerato-hyoid arises from the whole length of the thyro-hyal and 

 the segments which together form the posterior cornu of the os 

 hyoides ; the internal and deeper fibres are inserted into the proximal 

 end of the anterior cornu (cerato-hyal) for two thirds of its length ; 

 the external and more superficial fibres pass on to be inserted into 

 the side of the mandible in front and dorsad of the insertion of 

 the neuro-mandibularis, extending forward for nearly half its length ; 

 an additional bundle of fibres arises from the extreme distal end of 

 the cerato-hyal to join the last-mentioned fasciculus. Whether this 

 corresponds to the cerato-mandibular I am not sure from the memoir 

 on Iguana ; but on referring to the description of the myology of 

 Chamceleon parsonii by the same authorf, I find that it does not 

 exactly agree with any of the muscles of the throat in either of 

 those species. 



Omo-hyoid (figs. 1, 2 ,& 3, O.H.) arises from the inner surface of the 

 scapula, from aline going obliquely from the anterior to the posterior 

 edge ; and passing forward and ventrad, its superficial fibres are in- 

 serted into the posterior edge of the basihyal, while the deeper fibres 

 spread out and are attached to about two thirds of the distal end of the 

 thyro-hyal and the proximal end of its second segment; the muscles of 

 the two sides meet in a point at the middle line. 



There are two sterno-hyoids, as in L. belli. The one, very narrow, 

 arises from the sternum ventrad of the sterno-mastoid, and, passing 

 forward in front of the sterno-hyoideus profundus, is inserted into 

 the dorsal surface of the thyro-hyal close to its articulation with the 

 basihyal. The other, which appears to correspond to the sterno-hyoi- 

 deus profundus in L. belli, although in its origin it is more superficial 

 than the former, arises from a space on the ventral surface of the 

 sternum left vacant by the pectorales majores, extending for about one 

 third its length from the anterior edge of that bone. The muscles of 

 both sides meet in a point posteriorly in the mid line ; anteriorly each 

 spreads out into a broad and thin expansion, which is inserted into the 

 external half of the thyro-hyal. The single sternohyoid of P.ja- 

 ponicus % appears to correspond to the latter of the two preceding 

 muscles. 



* Loc. cit. t P. Z. S. 1870, p. 850. + Ibid. 1870, p. 414. 



