24 MISS J. B. TROCTER ON THE SKULL AND 



dowiiwarfls * ; when the jaws are closed the outer face of this 

 process is presented to the coronar}^ process of theaiigulo-splenial, 

 which it resembles in size and shape. This process seems to be 

 vei-y rare in the Anura, and until now has remained unnoticed. 



The quadrate cartilage pi'ojects in two strong condyles, well 

 beyond the extremities of the pterygoid, squamosal, and quadrato- 

 jngal bones. It is of massive build, and in the specimen figiu'ed 

 strougly ossified. 



The 2Ji'cemaxiU(e have ratlier long processes. Ventrally, at the 

 suture which they form with each other, thei'e is a shallow oval 

 pit. 



The maxiUce ai-e wide, strong, and slightlj^ rugose. Ventrally, 

 and close to the sutures which they form with the prsemaxillpe, 

 are round shallow concavities. ■ Posteriorly each is slightly 

 bifid, the inner border of the inner limb completing the squamoso- 

 maxillary suture, and the outer and longer branch forming a 

 wedge-shaped suture with the quadrato-jugal. 



The qitadrato-jugal is a small short bone ; its suture with the 

 maxilla is verj' diflicult to trace in old specimens. 



The mandibular arch. 



MeckeVs cartilage, where it articulates with the quadrate, ends 

 in a prominent down-curved knob. 



The angido-splenial leaves much of Meckel's cartilage exposed 

 to view ; its coronary process is Avell developed, and, as before 

 stated, lies face to face with the peculiarly similar process of the 

 pterygoid, from which it is only separated by the elevator 

 temjwralis muscle. 



The dentary at its distal end is raised into a slight tooth-like 

 projection, which, when the jaws are closed, fits into the shallow 

 pit at the anterior end of the maxilla which I have already 

 mentioned. 



The viento-mechelian bone forms a similar but larger projection 

 which fits into the median pit situated across the prfemaxillo- 

 pra^maxillaiy suture. 



The hygid apparatus. 

 As will be seen from text-fig. 1 d, the hyoid apparatus, thotigh 

 diftering slightly from that of R. temjioraria, is not peculiar in 

 any way. 



Summary and Conclusion as to the Affinities of 

 r. subsigillata. 



From the above description it will be seen that the skull of 

 7?. subsigillata differs almost in every particular from that of 

 R. temporaria, which, being the type of the genus, it is customary 

 to take as a standard. 



* Owing to tins oblique position it is slightly foreshortened in text-fig. la, h; a 

 better idea of its size cnn therefore be obtained from 1 c, where it is seen projecting 

 bdow the maxilla. 



