272 MESSRS. B. C. A. WIXDLE AN'D F. G. PARSOXS OX [NoV. 3, 



the hind-limb in walking, one notices that the knee is extended 

 and the ankle plantar flexed in order to lengthen the limb and so 

 pull and push the body of the animal over the spot on which the 

 foot is planted, while at the same time the knee is slightly flexed. 

 It is probable that the expansions from the hamstrings effect the 

 plantar flexion of the ankle by pulling up the calcaneal tuberosity, 

 at the same time that they are causing slight flexion of the knee. 

 An interesting and, so far as we know, unaccounted for structure 

 in the semitendinosus of Man, is the fibi-ous streak running across 

 the muscular belly ; this is seldom seen in the lower mammals, 

 and we have not noticed it in any Ungulate, although we have 

 carefully looked for it. Macalister, however, found it distinctly 

 in the Muntjac (27). The nerve-supply of the semitendinosus is 

 the special nerve to the hamstrings from the internal popliteal 

 element of the great sciatic (see text-fig. 26, p. 274). 



Biceps {Flexor cruris lateralis). — It has already been pointed 

 out how closely the biceps is connected with the femoro-coccygeus 

 in the Ungulata, and how constantly the latter muscle is inserted 

 into the side of the patella ; we shall therefore describe as biceps 

 only that part of the superficial lateral plane of muscle which is 

 inserted below the patella. As the muscle is so inseparable from 

 its neighbour the femoro-coccygeus (agitator caudse), it is very 

 difficult to say whether any of its fibres really rise from the caudal 

 vertebrae ; we are, however, inclined to agree with Lesbres that 

 in the Ungulates the biceps has only an origin from the tuber 

 ischii (see text-fig. 24, Bi.). Its insertion is into the fascia of the 

 upper half or more of the outer side of the leg, while from its 

 lower border a strong fibrous process passes down to the calcaneal 

 tuberosity, helping the gracilis and semitendinosvis to ensheath 

 the tendo Achillis. With the exception of relative size, there is 

 hardly any variety in the biceps of difierent Ungulates ; it perhaps 

 reaches its greatest development in the Tapir (58, 61, 62). 



Bicipiti accessorius {Tenuissimus). — This in most Ungulates is 



either suppressed or completely blended with the biceps. The 



only record we can find of it is that it is figured in Cuvier and 



Laurillard's Elephant (84), and may possibly be the deep part of 



"the biceps of the Tapir described by Murie (XVII.). 



Muscles of the Internal Femoral Region. 



Pectineus. — This muscle is often difficult to distinguish^ from 

 the adductor longus, especially as the latter may or may not be 

 delaminated from the adductor mass. The origin is fairly constant, 

 coming from some part of the ilio-pectineal line, while the insertion 

 seems to range all over the shaft of the femur. In the Hippopo- 

 tamus (1) Gratiolet describes three parts, pubic, symphysial, and 

 ischial ; of these the latter two are evidently adductor longus and 

 quadratus femoris. In the Suidse (6, 7, 11, 14) the muscle rises 

 from the whole ilio-pectineal line and is inserted into the middle 

 or distal part of the femur; it is comparatively small in this 



