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Show 184 DR. R. W. SHUFELDT ON [Apr. 1, cated, but believe with Hoffmann that the muscle can be very well described in its entirety, such as has been done in the present instance. 83. Gracilis.-This is a strong and rather thick ribbon of muscle that passes obliquely down the anteroinferior aspect of the thigh, its lower margin being in contact with the sartorius for its entire length. The gracilis arises from that process, immediately anterior to the acetabulum, which is crossed by the pubo-ischiadic suture, its origin being tendinous. For the most part it is inserted into the fascia covering the tibial side of the knee-joint, while a few of its fibres join those of the sartorius, the two muscles being very intimately united, here, at their insertion. Sanders found a gracilis as well as a sartorius muscle in both Liolepis and Platy-dactylus ; but Hoffmann seems disinclined to recognize the existence of the latter in Lizards (Bronn's • Thier-Reichs,' Rept. 22-24 Lief. 1881, p. 645). They are both undoubtedly handsomely developed here in Heloderma suspectum. 84. Sartorius.-In this we have a great muscular sheath that envelops nearly the entire ventral aspect of the thigh, and which arises from the hamular process of the pubis, as well as from the ilio-ischiadic ligament. Below, it is inserted into the proximal end of the tibia, upon its anterior aspect, just below the head of the bone. 85. Pelvo-tibialis.-There is a small muscle in this region that lies immediately beneath the gracilis for nearly its entire length, and which I will here describe under the name given it by Sanders. Prior to that writer, Mivart had designated it in the Iguana as the " tibial adductorf and subsequently Hoffmann termed it the " M. pubo-ischio-tibialis lateralis.'1'' Of these several names I the one bestowed upon it by Sanders to be decidedly the best one. In Heloderma it arises by a single tendinous head from the ischium just in front of the acetabulum. Passing down the antero-ventral aspect of the thigh as a narrowish ribbon of muscle, it again becomes tendinous as it nears the tibia, enters the popliteal space, and is inserted, just below its head, upon the mesial aspect of the bone just mentioned. 86. Semimembranosus.-What I describe here as the ilio-ischiadic ligament is a tendinous ligamentous arch which arises from the tuberosity of the ischium, and passing round the inside of the thigh to the front is there inserted into the ilium. From this arch our rather slender semimembranosus arises and passes down to be inserted into the outer side of the proximal end of the tibia. I can find no origin for it upon the ischium in Heloderma. 87. Semitendinosus.-This muscle is handsomely developed in our present subject. It arises, tendinous, from the ilio-ischiadic ligament, posterior to the line of the shaft of the femur. Becoming carneous it forms a fusiform muscle which is concaved towards the thigh and convexed upon its opposite aspect. Opposite the femoral condyles its tendon appears, and this is bifurcated, one branch going to the inner side of the proximal end of the tibia for insertion, the |
