1890.] HELODERMA SUSPECTUM. 183 



each case, that pass downwards and forwards. These appear to be 

 so many separate origins of the obllquus abdominis extenius, but 

 they do not properly belong to the series of the intercostals. They 

 pass across to become inserted into the transverse tendinous inter- 

 sections of the abdominal muscle to which we have referred. Where 

 the external intercostals are covered by the sacro-lumbalis, the two 

 muscles are very intimately fused together, but careful dissection 

 is all that is required to demonstrate their individual independ- 

 ence. 



80. Internal intercostals. — These are quite as well developed as 

 the external ones, and taken in mid-region they arise and are inserted 

 in the same manner as the more superficial set ; but in the present 

 case the fibres pass forwards and downwards, thus leaying con- 

 trary-disposed vacuities at the vertebral and iree ends of the ribs. 

 With respect to the intersterno-costal spaces, the fibres of the present 

 set of muscles are directed almost entirely inwards and but very 

 slightly forwards. 



81. Retrahentes costarum. — A large part of the thoracic parietes 

 and, continuous with it, nearly all of the abdominal parietes are amply 

 lined with strong, oblique muscular fasciculi. The first series of 

 digitations are supplied by the transversalis, and these interdigitate, 

 seriatim, with the fasciculi of the present muscle, and thus to- 

 gether they constitute a thick muscvdar lining to the internal body- 

 wall. 



The retrahentes costarum arise, upon either side, from the lateral 

 aspect of the bodies of the vertebrse for nearly the entire length of 

 the spine, from the post-cervical region down nearly to the sacrum, in 

 which latter locality the quadratus lumborum fulfils their part. 

 They pass obliquely forwards and outwards, to become inserted into 

 the middle of the shafts of the ribs upon their internal aspects, inter- 

 digitating, as I have already said, with the fasciculi of tlie transver- 

 salis. 



Muscles of the Sip-Girdle and of the Pelvic Limb. 



82. Iliacus. — A very interesting and broad sheet of muscle that 

 arises from within the pelvis, being attached, for the most part, to 

 the ventral and dorso-ventral surface of the pubis, as well as to the 

 median fibrous band that stands as a raphe between it and the fellow 

 of the opposite side. It may extend also slightly upon the ischium. 

 The fibres converging and passing over the pelvic brim, are inserted 

 into the anterior surface of the proximal extremity of the shaft 

 of the femur of the corresponding side, as well as into its trochanter 

 minor, and into that tendinous band seen to be crossing obliquely 

 the caput femoris, and into the fascia overlying the femoro-pelvic 

 articulation. 



Mivart, in his work upon the myology of the Iguana, considered 

 the present muscle to represent \\\e.psous and the iliacus combined, 

 and in describing it divides the same into some four or five parts. 

 In Heloderma I find these several parts more or less distinctly indi- 



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