DR. GUNTHER ON THE ANATOMY OF HATTERIA. 
619 
been recently treated of in a separate paper*. I have chosen for collateral examination 
Grammatophora , Iguana , Varanus, and Crocodilus (americanus, young, 18 inches long), 
and found the general arrangement of the muscles remarkably uniform. Dr. Haughton 
describes as a peculiarity of the Crocodile an interlacing of the tendons of various 
muscles, and says that the effect of it must be to produce simultaneity of action among 
them. Such a connexion of muscles by means of tendons has been described above as 
existing between the Extensor femoris caudalis and Gastrocnemius , and between a por- 
tion of the Flexor cruris (biceps) and Soleus ; but I have failed to find the connexion 
between the “ M. rectus and plantaris ” (so named by Dr. Haughton). 
Generally speaking, and not taking into consideration the numerous instances which 
might be adduced to the contrary, the actions of the limbs are less diversified in Saurians 
than in the higher classes of Vertebrata. The energy of the contractions of their 
muscles, although it may be momentarily great, is less enduring, so that the dispropor- 
tion between their feebly developed limbs and the size of the body appears only the 
greater. In accordance with this the muscles are found reduced in number, and sim- 
plified in their arrangement, inasmuch as muscles the origins of which are in close 
proximity are frequently partly confluent, or a fascicle of one muscle passes into the 
substance . of its neighbour. There is no doubt that such muscles act simultaneously ; 
but this want of separation refers to collateral muscles only. 
A want of separation of muscles belonging to different regions , such as the interlacing 
of the tendons of the muscles of the upper and lower legs, does not prove the simulta- 
neity of their actions, — first, because the connexion between them is effected by tendons 
more or less intimately attached to the bone, which interrupts the continuity of contrac- 
tion of the upper and lower muscles. Secondly, the simultaneity of action could not be 
produced without the simultaneous influence of the nerves entering those muscles ; and 
as it is dependent on the nerves, the tendinous connexion is not needed to produce it. 
It is a circumstance worthy of notice that all these interlacements are in the fossa poplitea, 
behind the knee-joint, which in Saurians is almost always in a state of flexion, and that 
these animals are able to draw the lower leg so far upwards as to lie alongside of the 
upper. This will readily account for the unusually high insertion of a part of the ten- 
dinous terminations of the lower muscles, at a place above and somewhat remote from 
the end of the femur, and more especially into the tendons of the upper muscles, there 
being no room on the bone itself. 
In Hatteria , as well as in other lizards, I have observed that parts of one and the same 
muscle are often so loosely united that it may be easily, though artificially, split from 
one end to the other, thereby tempting one to adopt a nomenclature created for higher 
Vertebrates with a more diversified action of the limbs and a greater multiplicity of 
distinct muscles. Thus the muscular system of the limbs of lizards appears to be cha- 
racterized not only by the partial confluence of the fascicles and tendons of different 
muscles, but also by the loose connexion of the fascicles of the muscles generally. 
* “ On the Muscular Anatomy of the Leg of the Crocodile. By the Rev. Samuel Haughton, M.D.,” in Ann, 
and Mag. Nat. Hist. 1865, vol. xvi. pp. 326-331. 
MDCCCLXVII. 4 P 
