270 MESSRS. B. C. A. WIXDLE AND F. G. PARSONS ON [Nov. 3, 



obturator foramen in the Horse, and this in spite o£ Lesbre's 

 assertion to the contrary. In the Tapiridse, too (61), we failed to 

 find it, and so did Murie (XYII.), who certainly would have been 

 on the look out for it since he was the original describer. It is 

 not described by any author in the Rhinocerotidse, but further 

 observation is necessary here. In the Elephant no mention is 

 made of it, though Miall and Greenwood (XXIX.) and Paterson 

 and Dun desci'il)e the obturators somewhat carefully. With 

 further opportunity for research we believe that it will be found 

 that the obturator externus passes through the foramen in the 

 Artiodactyla and Procaviidse, but that it does not do so in the 

 Perissodactyla and Elephantidas. 



Quadratus femoris. — This muscle varies a good deal in size in 

 difierent Ungulates, but it is usually present. Owing to the 

 horizontal position of the pelvis, it passes obliquely from the tuber 

 ischii to the back of the upper part of the shaft of the femur so 

 as to form an X with the tendon of the obturator externus ; it is 

 usually somewhat constricted at its insertion, so that the name 

 quadratus femoris used in human anatomy does not very aptly 

 describe it. It is especially large in the Hyrax (74, 75), and in 

 one Sheep (46) (see text-fig. 25) it was found to be double, but this 

 does not seem to be always the case. Among the Perissodactyla 

 it is not well developed ; in the Horse (63) it is quite small, and 

 Meckel (VII.) says absent altogether. In the Tapir (61, 62) it is 

 also small, while in the Rhinoceros (71) Haughton failed to find 

 it*. In all the other animals on our list the muscle was present, 

 and in the Duiker-bok, Sheep, and Harnessed Antelope was 

 supplied by a branch from the sacral plexus as in Man. 



Muscles of the Posterior Femoral Region. 



Semimembranosus and Presemimemhranostcs.- — These muscles 

 have the usual mammalian attachments ; they are always fused at 

 their origin from the tuber ischii; and it is characteristic of 

 ungulates that this fusion continues much lower down the thigh 

 than it usually does in other mammals. This is the case in the 

 Hippopotamus (1), Pig (4, 11, 14), Chevi^otain (21, 22), Deer (26, 

 29, 30), Ox (36, 40), Sheep (41, 46, 47), Goat (50, 52), Antelope 

 (54, 55), Tapir (58, 61), Rhinoceros (71), Hyrax (74, 75), and 

 Elephant (81, 84,85). Meckel (VII.) and Lesbres (V.) point out 

 that in the ruminants the origin is entirely ischial, while the 

 Horse has a caudal origin besides ; we think that we are justified 

 in broadening this generalisation and in saying that in the Artio- 

 dactyla there is only an ischial head, while in the Perissodactyla 

 and Subungulata ischial and caudal heads are found (see text- 

 figs. 24 & 26, S.M.). 



The semimembranosus has the usual mammalian insertion by a 

 rounded tendon deep to the internal lateral ligament : in the 



* The dissection of this animal seems to have been carried out nnder great 

 difficulties, so that the muscle may have been overlooked. 



