408 MR. ST. GEORGE M IV ART AND DR. J. MURIE [June 2G, 



part very intimately united (figs. 4 & 5, J5.). The anterior portion 

 arises from the sacral verteb ice, and is strongly muscular at its origin; 

 superficially fibres pass on to the outside of the heads of the tibia 

 and fibula, mingling with those of the broader second portion ; but 

 deeply this portion of the muscle terminates in a flat, thin and nar- 

 row tendon, which is inserted into the outer side of the patella. 



The second portion originates by a very strong but short tendon 

 from the outer side of the tuberosity of the ischium, and, expanding 

 into a broad sheet of muscle, is inserted by aponeurosis into the out- 

 side of the leg down to the ankle. 



It thus seems that the tensor vaginae femoris, gluteus maximus, 

 and the two parts of the biceps form together an almost continuous 

 investment or sheet of muscle from the crest of the ilium to the 

 caudal vertebrae and ischium, and from the patella to the ankle : 

 together most powerfully flexing the limb. 



In the Guinea-pig the arrangement is very similar, except that 

 the two parts are rather more distinct and that the anterior portion 

 is narrower. 



In the Hare the two parts are very distinct, and the tendon of the 

 anterior portion to the patella is much stronger and longer. The 

 posterior portion presents no essential difference in attachments ; but 

 the muscular sheet, which in the two former animals extends to the 

 ankle, in the Hare is much more aponeurotic. 



The semimembranosus, unlike the condition of this muscle in 

 Hyrax*, arises singly; but it agreed in being an uncommonly large 

 muscle. It has origin from the whole of the triangular space (or 

 tuberosity) of the ischium, and is inserted broadly from the inner 

 condyle of the femur to the head of the tibia (fig. 4, S. m.). A 

 slight dissection, moreover, shows a division at its insertion into three 

 portions, as in Man. The middle one is more or less formed by a 

 distinct round and strong tendon, which springs from a separate 

 belly of muscle more or less surrounded and enclosed by the rest of 

 the semimembranosus. 



In the Guinea-pig, Hare, and Rabbit this separation, as it were, 

 into two muscles is more strongly marked ; in the two last the fleshy 

 insertion of the largest portion into the tibia is not so extensive as in 

 the Agouti and Guinea-pig. It is relatively very large in the latter. 



Semitendinosus. Strong and bulky, it has two origins. The 

 first arises by fleshy fibres from the caudal vertebrae as far back as 

 opposite the tuberosity of the ischium, the fibres adhering to the 

 deep fascia in the interspace between these two points. 



A second head, much smaller than the preceding, but also mus- 

 cular, comes from the tuberosity of the ischium, and immediately 

 joius the larger head. 



The anterior border of the first head is closely adherent to the 

 posterior border of the gluteus maximus. Insertion : by a broad 

 translucent strong sheet of tendon the whole length of the shaft of 

 the tibia to os calcis (figs. 4 & 5, St.), as mentioned on the opposite 

 page in the description of the gracilis. 



* P. Z. S. 1865, p. .'!47. 



