274 CAPT. D, M. S. WATSON ON SEYMOURIA, 



skull. It has a long suture with the pterygoid, is bounded 

 posteriorly by the transverse, and in front forms certainly the 

 back and appai-ently also a large part of the lateral margin of 

 the internal narial opening. 



Its most interesting feature is the presence of a pit surrounded 

 by an upstanding ridge, lying on the palatal surface just posterior 

 to the nostril. This pit contains two lai-ge tusks, which replace 

 one another so that normally only one is functional at once. 

 The whole arrangement is identical with the large palatine tusks 

 and their pits iru Labyrinthodonts. It is remarkable that this 

 tooth has only been described by Cope in Conodectes. It is well 

 shown also in Munich A and my skull. 



Prevomer. — Only the posterior end of the prevomer is known. 

 The two separate the internal nares and articulate with the 

 anterior ends of the pterygoids. 



Qtmdrate. — An incomplete but isolated and extremely well- 

 preserved left quadrate belongs to my young West Coffee Creek 

 specimen-. It has a well-ossified and rounded articular margin 

 rather conspicuously divided into two condyles. The anterior 

 face is concave. The outer side is entirely occupied by a sutural 

 surface for the quadrato-jugal and squamosal, and the inner 

 retains the impression of the tip of the quadrate ramus of the 

 pterygoid. The exposed posterior surface is triangular and bears 

 an irregular knob. 



Ductus naso-lachrymalis. — My skull shows quite clearly the 

 presence of a naso-lachrymal duct lying within the substance of 

 the lachrymal and extending from the orbit to the nostril. 



Septomaxilla. — Whilst removing the matrix from the sym- 

 physial region of the mandible of my skull, I found a single 

 septomaxilla which had obviously dropped down through the 

 posterior naris. 



This element is a thin plate of bone bent round so as to clasp 

 Jacobson's organ, and has a flat face for articulation with the 

 dorsal surface of the prevomer. 



Lower jaw. — My skeleton retains the right ramus of the lower 

 jaw from the symphysis to behind the anterior end of the supra- 

 meckelian fossa. Both inner and outer sui'faces are well exposed, 

 and a fortunate fracture along a horizontal plane lying just above 

 the upper surface of the cavity of the jaw, which passes through 

 the dentary and the three coronoids, places the structure beyond 

 doubt, as it permits a definite distinction between sutures and 

 cracks. The sutures are usually very visible, being filled with red 

 iron oxide and the bone white. 



Articidar. — Both articulars of the yoimg specimen from Coffee 

 Creek are preserved. 



The bone is very short and ends anteriorly in a flat face con- 

 tinued in life by the remains of Meckel's cartilage. 



The articvilar surface is convex from back to front and is 

 divided into two areas, corresponding to the condyles of the 

 quadrate, by a low ridge running obliquely across. 



The outer face has a deeply depressed sutural area for the 



