460 



unfrequently), in the tibialis antieus rarely, and in the tibialis pos- 

 ticus. 



The biceps flexor cruris in the lower limbs of a male subject arose 

 not only by their long heads from the tuber ischii, but these were con- 

 tinued upwards and backwards over the great sciatic ligament to the 

 side and lower border of the sacrum. 



IY. Abnormalities of coalescence may occur in two ways — either by 

 the fusion, more or less complete, of the opposed margins of neighbouring 

 muscles, or by the presence of connecting bands, uniting muscles which 

 typically are distinct. The latter mode of connexion is the more fre- 

 quently met with ; but the two varieties often merge into each other. 

 The former I have seen in the following muscles : — 



1. The anterior belly of digastric and its fellow of the opposite 

 side I have seen to unite, so as to form one mass of interlaced muscular 

 fibres, either closely united to the mylo-hyoid, or in other instances 

 separated from it. This arrangement is the normal state in Inuus 

 sylvanus, and in a few other species of Quadrumana. A partial form of 

 this variety I have also seen, in which the left anterior belly sent a 

 very large fasciculus below the chin to the median line, there to be 

 inserted into the fascia. 



2. I have in one instance found the anterior belly of digastric, on 

 the right side, inseparably connected to the mylo-hyoid of its own side, 

 with which its fibres interlaced. 



3. The two genio-hyoid muscles several times were absolutely 

 inseparable, there being no trace of the usual cellular raphe between 

 them. The same mode of fusion is the usual arrangement in the motor 

 uvulae. 



4. The trapezius and deltoid have been in my experience several 

 times united by tendinous and fleshy fibres, crossing the spine of the 

 scapula. The complete union of these muscles is very common in the 

 non-claviculate Mammals, especially at their internal extremity. 



5. The infraspinatus and deltoid were in one case fused together, 

 as occurs partially in the pig and camel. The union was produced by 

 the lower fibres of the former muscle becoming continuous with the 

 posterior fibres of the latter. 



6. The outer border of the clavicular fibres of the great pectoral 

 and the inner edge of the deltoid I have seen partially fused together, 

 especially at their lowest part. The same arrangement I found in 

 Cynocephalus. I have never met with a complete fusion of the above 

 muscles in man, but a case of the kind is described by Koster ("Neder- 

 landsch Archief," 1864). 



7. The deltoid and supinator longus muscles were perfectly 

 blended in the left arm of a strong, well-developed subject, so that a 

 band three quarters of an inch broad, and half an inch thick, was con- 

 tinued from the acromion process to the tendon, which was inserted into 

 the rough surface above the styloid process of the radius. 



