618 
DR. GUNTHER ON THE ANATOMY OF HATTERIA. 
outermost layer consists of two muscles equivalent to the MM. soleus (l) and gastrocne- 
mius (k), although their origins are somewhat modified*. The M. soleus occupies the 
tibial side, and arises from the upper end of the tibia, emitting a tendon which is con- 
fluent with the slender portion of the great flexor ( biceps 1) of the femoral region ; it 
terminates in a broad tendon thinned into a fascia extending across the tarsus, and chiefly 
attached to the astragalus on one side and to the metatarsus of the fifth toe on the other. 
In order to have a full view of the M. gastrocnemius , it is necessary to remove the soleus ; 
it is much larger than the soleus, and occupies the fibular half of the lower leg ; it has 
two heads; the larger arises from the femur and long tendon of the extensor femoris 
caudalis , and passes, in the tarsal region, uninterruptedly into the jlexor digitorum 
communis brevis, the division between both muscles being faintly marked by a transverse 
tendinous inscription. The second head is very slender, and arises from the tendon of 
the great flexor of the femoral region, being confluent at its origin with the M. soleus. 
The second layer consists of the flexor digitorum communis longus only ; but this 
muscle has three heads, which are united into an exceedingly strong tendon in the tarsal 
region, which, as usual, is split into five branches, each perforating the corresponding 
branch of the short flexor. The longest and most superficial of the three heads is 
confluent with the large head of the gastrocnemius, both having the same origin on the 
femur. The second head is situated below, and covered by the first, and arises from the 
upper ends of tibia and fibula. The third head is additional, and may be regarded as a 
separate muscle, running and working in a quite different direction from the others ; it 
is flat, rhomboid, and arises from the outer edge of the lower end of the fibula and of 
the tarsus, runs transversely to the longitudinal axis of the limb, and meets the common 
tendon at an angle of 45° : whilst the two longer heads of the muscle act and bend the 
toes in the direction of the longitudinal axis of the bone, the action of this short head 
crosses it obliquely, and bends the three inner toes only. 
The third layer consists of the M. tibialis posticus ; it arises from the entire posterior 
side of the tibia, its fibres descending obliquely, and converging into a broad tendon 
inserted into the metatarsals of the three inner toes ; it draws the foot backwards and 
inwards. 
The space between tibia and fibula is filled by a muscle the fibres of which run trans- 
versely from one bone to the other. 
The muscles of the foot agree perfectly with those of Grammatophora and Iguana , of 
which latter lizard they have been described by Meckel f. 
I have given a detailed description of the muscles of the extremities, not in the hope 
of finding any peculiarity by which Hatteria might be distinguished, or which might assist 
in determining its affinities, but because little attention has been paid to the special 
myology of Saurians, and because the muscles of the hind limb of the Crocodile have 
* Dr. Hatjghton appears to have named the M. gastrocnemius Plantaris, and the M. soleus Gastrocnemius. 
t System d. vergl. Anat. vol. iii. p. 285. 
