486 Mr. J. Wood on Variations in Human Myology. [June 18, 



In 102 subjects examined by the author, the anterior belly of this 

 muscle has been found double in 5 out of 68 males^ of which in 2 the 

 supernumerary belly decussated with its fellow across the median line. 

 Out of 34 females it was found double once only on the left side. 



In the Norway Rat {^lus decumanus), the anterior bellies of the di- 

 gastric are completely blended together, arising without any median fissure 

 from an arched tendinous structure connecting the two median tendons. 

 They are also united in the Cercopithecus sahcEus, according to Rudolphi 

 (Heusinger's Zeitschrift, Bd. iii. S. 33.5), and blended so as completely to 

 cover the mylo-hyoids in Callithrix and Papio Mormon (Cuvier and Lauril- 

 lard's plates). More or less so they are found in the ruminants. 



In the male subject No. 2, a combination of curious varieties led to 

 the sketch of the adjoining figure (fig. 2), taken by the author from the 

 dissected parts. The posterior 



belly of the digastric («) appeared Fig. 2 (Subject No. 2). 



at first sight to be a triple muscle. 

 The two anterior muscular slips 

 {b & c), which were implanted upon 

 the median tendon, one behind the 

 hyoid pulley with the true poste- 

 rior belly, and the other in front of 

 it and nearer to the anterior belly 

 (d), were found on closer exami- 

 nation to arise from the styloid 

 process, the hinder one (b) from 

 the usual site of origin of the stylo- 

 hyoid muscle, and the front one 

 (c) from the tip of the process with 

 the stylo-glossus. Each of these, 

 therefore, represents the two halves 

 of a completely split or divided 5^3/^0- 

 hyoid, which, instead of uniting to 

 be inserted into the side of the hyoid bone, are implanted separately upon 

 the tendon of the digastric. Coexistent with this were two other abnor- 

 malities which may most conveniently be described here. One was a 

 curious well-developed muscular slip, found only on the left side, arising 

 as a muscle one-sixth of an inch wide (e), from the lower genial tubercle 

 of the mandible outside the genio-hyoid muscle {g). Tbence passing 

 upward and backward over the genio-hyo-glossus and hyo-glossus muscles, 

 it finally united its fibres with those of the stylo-glossus (f) at their 

 insertion into the outer and back part of the tongue. This muscle, which 

 the author has never before met with nor found recorded, is totally 

 different from the mylo-glossus described in his last paper. It also differs 

 from that mentioned under this name by Bohmer (Obs. x\nat. rar. praefat. 

 viii. note 5), as seen by Vesahus, Riolanus, and Spigelius, and considered 



