1867.] 



MYOLOGY OF IGUANA TUBERCULATA. 



773 



vance obliquely forwards towards the middle line of the body, those 

 arising most anteriorly being the longest. The muscle extends for- 

 wards more than halfway from the pubis to the sternum. 



Transversus perinei (fig. 14, T.Pr.). This is a thick triangular 

 muscle, arising from the side of the os cloacae and from the tendi- 

 nous arch before mentioned passing to the ilium. It fuses more or 

 less completely with the posterior part of the origin of the semimem- 

 branosus. 



Caudal Musclks. 



The essential nature of the true caudal muscles is best seen at about 

 the middle of the tail (fig. 4). There the muscular mass of each 

 lateral half of the tail, is easily demonstrated to consist of four lon- 

 gitudinal series of muscular and tendinous cones, the series beino- 

 placed one above another, and all the cones having their apices di- 

 rected forwards. 



Fig. 4. 



Diagram of aiudal muscular cones of the right side of the tail. 

 1. Dorsal lateral cone. 2. Upper median lateral cone. 3. Lower median late- 

 ral cone. 4. Ventral lateral cone. h. liiferior spine. N. Neural spine. 

 t. Transverse process, z. Zygapophyses. 



Four such cones appear to spring from each side of each caudal 

 vertebra ; but their length generally exceeds that of two such ver- 

 tebrae. The base of each cone is aponeurotic, with the superficial 

 part glisteningly tendinous. The apex of each cone is muscular. 

 Each cone being hollow, it receives into its cavity the muscular apex 

 of the cone next behind. The repetition of this serial enclosure 

 gives rise to the four longitudinal rows of cones ; and as the aponeu- 

 rosis of each cone is more or less incomplete on its external surface, 

 the tendinous margins of the aperture appear as two glistening lines, 

 which converge anteriorly ; moreover, the bases of the cones being 

 on the same vertical line, the appearance of numerous acutely zigzag 



