1001.] THE HUSOLSa OF THE FXGFLATA. <>(>7 



tendon is present but unattached to the hyoid. Bronn (VI.) says 

 that the anterior bellies are always connected with one another in 

 Ruminants ; and Chauveau (II.) describes a small square muscle in 

 the Ox which passes transversely across, uniting the two digastrics 

 by parsing beneath the base of the tongue. Our own experience, 

 based on the Ox (36), Sheep (42, 43, 45), and Duiker-bok (49), 

 shows us that this union across the middle line is not a charac- 

 teristic mark of the Bovidffl as a family, 



In the Tapiridffl (52. 52 a, 54) the muscle is very strong and is 

 inserted into the posterior half of the lower border of the mandible, 

 but there is no central tendon at all, 



In the Equidae (56, 57, 58, 61) the muscle divides immediately 

 after its origin from the paroccipital : one part goes to the border 

 of the ramus of the mandible just above the angle, while the other 

 forms the normal posterior belly of a typical digastric and is sepa- 

 rated from the anterior belly by a definite central tendon. The 

 insertion of the anterior belly is a good deal nearer the symphysis 

 than it is in most other Ungulates. Among the Subungulata the 

 Hyrax (67. 6 s ) has the origin of the digastric chiefly from the 

 paramastoid : as it goes forward the muscle spreads out like a fan 

 to be inserted into the greater part of the lower margin of the 

 body of the mandible from the angle forward. Abont two thirds 

 of the way from the origin is a narrow zigzag tendinous streak. 

 the only representative of a central tendon. 



In the Indian Elephant (73, 74. 75, 70, 77) the muscle runs 

 from the paroccipital to the jaw in front of the .angle, but there 

 is some difference of opinion about the central tendon. Mayer 

 (XXVIII.). Watson (XXX.), and Young (XXXI.) found one. but 

 Miall and Greenwood (XXIX.) and Cuvier and Laurillard (I.) did 

 noi -ee it. Miall and Greenwood's description seems somewhat 

 complicated, but we have little doubt that they have included the 

 -tylo-hyoid and masto-styloideus with the digastric. 



From the foregoing description it will be seen that the digastric. 

 as in other orders, is of some classificatoi'y importance : thus in the 

 Hippopotamus and Suida? the posterior belly is often suppressed. 

 In the Tapiridaa the central tendon is absent. In the Hyracoidea 

 ii i^ a mere zigzag streak. In the Elephantidae it may be present 

 or absent. In the Equidae a part of the posterior belly i< inserted 

 into the ramus of the jaw, while in the C'ervida 3 the tendon i^ 

 better developed than in any oilier family. 



Mtuelea attached i<> th< Hyoid Bone. 



Mylo-hyoid.— This muscle has the usual attachments, though it 



does unt in ill cases ran forward as far a- the symphysis; this is 

 especially seen in the Suids (11, 12, 14). In the Elephant, .Miall 

 and Greenwood (74) say thai the muscle is attached to the great 



con i u of tin- hyoid and to a tendinous arch which crosses the thyro- 

 hyoid tic ml) ra ne. Chain kiii ( I I.) and Lesbres (V.) notice that in 

 Ruminant* two plane- are found, and our Own dissections hear this 



