960 THE OSTEOLOGY AND MYOLOGY OF THE DEATH ADDER, 



The muscle arises from the anterior portion of the hyoid rod, 

 and runs forward to be inserted into the floor of the mouth close 

 to the insertion of the genio-trachealis, while many of its fibres 

 are attached to the trachea. 



This muscle is probably a dismemberment, like the genio- 

 trachealis, of the genio-glossus. 



The Transversalis Stratum. 



The transversalis stratum of the ventral muscle is well deve- 

 loped in snakes. If we lay open the abdomen, and turn aside the 

 intestines, we see a well marked column of muscle lying on either 

 side of the haemal spines, whose fibres run forward and outwards ; 

 the columns are composed of the depressores costarum. On 

 removing these muscles, we come on a levator layer, running from 

 before backwards; these represent a subvertebral rectus. On 

 either side of the depressores, we have the transversalis muscle 

 and fascia lying in a sheet beneath the ribs, and hiding from 

 view the retrahentes costarum running from before, backwards, 

 and outwards. We do not find any internal intercostals, their 

 place being taken by the depressores and retrahentes, which we 

 regard as greatly altered internal intercostals. 



If we trace the depressores forward we find them being converted 

 into longus colli and rectus capitis anticus. 



M. TRANS V^ERSALIS. 



31. abdominis externus et internus, Hoffmann ; Der dussere 

 Bauchmuskel^ und der innerere Bauchmuskel, D'Alton ; M.. trans- 

 versalis, Owen. 



The transversalis muscle proper is represented by two sheets of 

 muscle, which spring from the junction of the outer with the 

 inner half of the inferior surface of the ribs, just external to the 

 insertion of the depressores costarum. Two layers composing the 

 transversalis run downwards and inwards, the muscular fibres 

 gradually giving place to a strong tendon which meets its fellow 

 of the opposite side along the middle ventral line. 



