546 MR. T. GOODEY OX THE SKELETAL [Mar. 15, 



oval excavation mentioned by Garman. In two cases out of three 

 which I have examined, this communicates with the dorsal 

 surface of the basihyal by means of a small round aperture at the 

 anterior end of the concavity. In the third case, the excavation 

 is not covered above by cartilage but was found to open directly 

 into a slightly smaller concavity on the dorsal surface of the 

 cartilage. The thyroid gland is situated in the hollow excavation 

 on the ventral side, and in one example examined, a very in- 

 teresting tubular structure, attached to the gland and communi- 

 cating with the oral cavity, has been discovered. This is dealt 

 with in a separate paper*. 



A strong ensheathing fibrous ligament wraps the inner side of 

 the quadrato-mandibular joint. It is continued on to the outer 

 side of the joint and then proceeds backward to wrap the distal 

 end of the hyomandibular and the proximal end of the ceratohyal, 

 both of which are somewhat closely applied to the jaw joint (fig. 4). 

 It is by this ligament that the hyostylic suspension of the jaws is 

 is brought about. The ceratohyal is very closely applied in the 

 greater part of its length to the inner side of the mandible where 

 it fits into a sort of shallow groove. It is held firmly in its 

 position by means of two important ligaments, in addition to the 

 one just described which connects its proximal end with the 

 angle of the jaws. Of these two ligaments one is external and 

 the other internal in position. The former stretches between a 

 process on the outer ridge of the ventro-posterior side of the 

 mandible and a corresponding ridge on the outer edge of the 

 ceratohyal. It is about half an inch in width, and may be termed 

 the ligamentum hyoideo-mandihulare externum. The inner one is 

 a broad, flat ligament (fig. 5) attached at its upper end to the 

 convex inner surface of the proximal end of the palatoquadrate 

 cartilage, and, stretching across the jaw joint and the mandible, 

 is inserted along the ridge on the inner and upper side of the 

 ceratohyal. It may be termed the ligamentum quadrato-hyoideo 

 internum. 



The disposition of the head muscles has been dealt with by 

 Furbringer (6), but the more important ridges and processes on 

 the skull and jaws, which serve for the attachment of these 

 muscles, are also worthy of some attention, seeing that they are 

 quite pronouncedly developed. It will perhaps be easier in 

 dealing with these to take the muscles separately and describe 

 their relations to the particular ridges of attachment. 



Levator maxilloe is attached above to the thin ridge (s.c.s.) (t. 

 in Garman, PI. viii. fig. A) which projects over the auditory 

 capsule, and to the posterior edge of the postorbital process. 

 It extends in front of the spiracle and is inserted on the inner 

 and upper edge of the prominent ridge (pq.r.) along the dorsal 

 side of the quadratic portion of the palatoquadrate. This in- 

 sertion extends as far backward as the hyal process. 



* Goodey, T., "Vestiges of the Thyroid in Chlamt/doselacJms anguineus,ScyUium 

 calulus and S. eanicula." Anatomischer Anzeigev, Rd. xxxvi. 1010. 



