430 MR. F. E. BEDDARD ON THE [June 3, 



convinced that myology is a most valuable aid in determining the 

 affinities of different genera, and even groups, of birds, its use in my 

 opinion is restricted to this ; no wider inferences can be drawn with 

 any degree of safety. 



The semimembranosus arises deep of the semitendinosiis, from the 

 ischium ; it is a tolerably strong muscle, though slighter than the 

 semitendinosiis ; it is inserted by a broad flat tendon considerably 

 below the insertion of the semitendinosiis on to the tibia. 



The relative positions of the insertions of this muscle and of the 

 Semite ndinosus are shown in the drawing (Plate XXXIX. fig. 3 ; 

 and more in detail in fig. 3 a). As Garrod [2] has pointed out, this 

 muscle is usually very thin in the Grebes and may even \ as stated 

 by Sundevall, occasionally disappear. 



I find, however, in some notes left by Prof. Garrod that Colymbus 

 glacialis has a large semimembranosus " twice the size of semitendi- 

 nosus." Its origin appears to bo a little peculiar ; it arises from the 

 ilium and ischium near to the posterior end of the pelvis . 



The femora-caudal is a strong and well-developed muscle which has 

 the usual origin and ends by a narrow thin tendon of insertion. 



The accessory femoro-caudal is a short fleshy muscle which is in- 

 serted in commou with the femoro-caudal (as shown in Plate XXXIX. 

 fig. 3) ; it appears as if inserted on to the tendon of the latter. 



The adductor muscles appeared to me to be comparatively small 

 in size ; the lower of the two was largely tendinous. 



The (jastrocnemius arises by three heads : the outer head is a 

 large fleshy muscle arising by a thin and strong tendon from the 

 femur, and also by a few muscular fibres from the fascia covering the 

 leg, which has already been spoken of in connection with the biceps ; 

 the inner head is of equal size and arises from the cnemial crest of 

 tibia, from fascise covering the leg, from septum between itself and 

 the peroneus longus ; its tendon joins that of the outer head at the 

 tendo AchiUis. The middle head is a very tiny muscle with a very 

 long tendon of insertion ; it unites with that of the inner head before 

 the latter joins the tendon of the outer head of the gastrocnemius. 



There are two peronei muscles which have the usual relations ; 

 the tendon of the longus fuses with the tendon of the superficial 

 flexor of the third digit. 



The ijeroneus brevis is a large muscle which forms a kind of 

 sheath round the tibialis anticus and the other muscles which 

 spring from the front of the leg ; its flat, rather broad tendon, 

 appears to be inserted on to the heel in the usual fashion. 



The tibialis anticus has the usual two heads, one femoral, the 

 other tibial; its tendon just before its insertion into metatarsus 

 gives off a small branch to the fascia which covers over the tendon 

 of extensor communis. 



According to Giebel's [6] notes upon the myology of Heliornis 

 surinaniensis, the pectoralis primus and secunclus agree with the 

 same muscles in Podica ; he mentions also the large " musculus 

 gracilis" { = a7nbiens). The peroneus longus has evidently the same 

 relations, and is, as in Podica, a large muscle. The description of 

 ' Garrod. MS. (In rarlkcpf miiwr). 



