354 MR. p. CHALMERS MITCHELL OX THE [May 7, 



most external portion is the largest. It arises fleshy from a 

 curved line over the ear from the posterior edge of the orbit to the 

 edge of the hiventer maxillce. Its fibres run downwards and for- 

 wards under the maxilla, to be inserted along the inner edge of the 

 mandible. The second portion is the most anterior. It is a com- 

 tively narrow band, sti-ongly tendinous, passing from the posterior 

 inner Avail of the orbit near the postorbital process : its fibres run 

 downwards and outwards, and, passing under the maxilla, are 

 inserted into the mandible internal to the first portion. The third 

 portion lies behind the second, and is shorter. It arises from the 

 under edge of the orbital process of the quadrate, and, passing 

 parallel to the second portion under the maxillary bar, is inserted 

 into the inner side of the mandible. 



The fourth portion does not act as an elevator of the lower jaw. 

 It is a broad fleshy mass, deep within the orbit, passing from 

 behind the optic foramen to the upper and inner edge of the 

 orbital process of the quadrate. 



Pterygoid. The first portion is muscular only at its origin from 

 the internal articular process of the lower jaw. It becomes a 

 strong superficial band of tendon, which in front spreads out in 

 the strong membrane covering the palate. The second portion is 

 abroad muscular mass arising from the internal articular process all 

 along its length. The fibres run forwards and are inserted to the 

 pterygoid and the ventral surface of the palatal bones. The third 

 portion is a broad mass external to the second ; it arises from 

 the inner face of the lower jaw behind the second portion, and 

 running forA^ards and inwards is inserted to the outer and upper 

 surfaces of the palatal bone. 



The Hyoid Group. 



Mylohyoid anterior. The two divisions seen in Palamedea were not 

 marked ; the muscle, which was well marked, ai'ises from the inner 

 side of the lower jaw anterior to the region of the basihyal. The 

 fibres run straight across the surface of the lower jaw and meet 

 their fellows of the other side in a median raphe. Some of the 

 posterior fibres spread out as a diffuse sheet. 



Mylohoid posterior. The origin was as in Palamedea. The pos- 

 terior thinner portion was exactly as in Palamedea, where we 

 described it as a platysma myoides. The narrower anterior portion 

 was a stout ribbon of muscle running forwards and inwards 

 superficial to the ceratohyal, to be inserted to the inner surface of 

 the base of the cornu and to the outer surface of the urohyal, in 

 fact to the angle formed by the meeting of these two parts of the 

 hyoid apparatus. 



Geniohyoid. As in Palamedea this muscle was wrapped round 

 the posterior portion of the cornu of the hyoid, and then passed 

 forward to be inserted to the inner surface of the lower jaw behind 

 the anterior mylohyoid. 



Genioylossus absent, as in Palamedea, 



