1872.] MR. A. SANDERS ON LIOLEPIS BELLI. 173 



Coccygeus inferior (figs. 10 & 13) appears as a continuation for- 

 ward of the inferior section of the caudal muscles ; it arises from the 

 extremities of the haemal spines of the caudal vertebras from the tenth 

 to the third ; posteriorly it is superficial to the pyriformis. It is in- 

 serted, partly muscular and partly tendinous, into the extremity of 

 a triangular apophysis which exists on the posterior border of the 

 ischium. 



Retractor cloacce (fig. 9) arises from the under surfaces of the 

 transverse processes of the caudal vertebrae from the ninth to the fifth ; 

 it commences as a thin muscular slip ; and passing forward it gra- 

 dually becomes thicker, and, crossing superficially the ventral surface 

 of the pyriformis, is inserted into the outer angle of the cloaca. This 

 muscle is peculiar ; it has a somewhat flattened shape, and encloses 

 in its interior a flat membrane, composed of a sort of elastic tissue, 

 rolled up longitudinally into a cylindrical form. 



Pyriformis (fig. 1 0) arises from the under surface of the transverse 

 processes and from the hsemapophyses of the caudal vertebrae from 

 the twenty-second to the third inclusive ; the posterior fibres pass for- 

 ward, and the anteriorones outward, toendin a broad flat tendon, which, 

 passing over the trochanter of the femur, is inserted into the ventral 

 aspect of the bone at its base, immediately outside and distad of 

 the ilio-femoral articulation. Before reaching its insertion this tendon 

 gives origin to a narrow one, which, passing down the thigh and 

 behind the knee-joint, joins the tendon of the gastrocnemius, and, 

 continuiug its course, is inserted into the back part of the fibula, close 

 to the insertion of the pelvo-tibialis, which is at the contiguous point 

 of the tibia ; the ilio-ischiatic ligament passes superficially to this 

 muscle, and forms a sort of pulley for it. Meckel * remarked of this 

 muscle, that it "entspricht dem birnformigen Muskeldes Menschen;" 

 but Cuvierf objected to this interpretation, on the ground that it is 

 inserted into the lesser trochanter ; and this objection has a good deal 

 of force, as the apophysis in this specimen really appears to corre- 

 spond more with the lesser than with the greater trochanter ; but the 

 muscle is not actually inserted into this process, but more towards 

 the outside of the bone. 



Capsularis (fig. 14). This small muscle, which appears almost as 

 apart of the coccygeus inferior, arises from the internal surface of the 

 posterior triangular process of the ischium, and, passing behind the 

 ilium, is inserted into the upper and posterior surface of the head of 

 the femur, close to the acetabulum, and tends to keep the head of the 

 bone steady in its socket. 



Obturator externus (figs. 10 & 13) arises from the middle line of 

 the external surface of the ischium, on the ventral aspect of the 

 pelvis, and from the posterior half of the inner border of the ischio- 

 pubic foramen covered by the pectineus ; the fibres converge, and, 

 passing over the trochanter between the pyriformis and the head of 

 the femur, turn round towards the dorsal aspect of the bone, and are 

 inserted on that side close to the capsidar ligament. I have ven- 



* Vergleichende Anatomie, Theil iii. pp. 152, 153. 



t Le9ons cV Anatomie Compare, torn. i. p. 296, 2nd ed. 



