18 Mr. W. P. Pycraft on the 



external lateral ridge which runs forward from the base to 

 the middle of the shaft in such genera as Tardus, Pratin- 

 cola, and Erithacus, for example. It differs, too, from the 

 coracoid of Sialia, firstly, in that the width at the base is 

 greatly increased in Sialia by the development of a large 

 lateral plate formed by the expansion of the external angle of 

 the base of the shaft ; and, secondly, in that, while in Sialia 

 the acrocoracoid (fig. 8 B, a.c, p. 17) is well marked, and at its 

 free end turns inwards and downwards to form a hammer- 

 shaped process grooved on its inner surface for the furcula, 

 in Zeledonia this region of the coracoid is much reduced, and 

 has the hammer-shaped process reduced to a hook-shaped, 

 which is not grooved for the furcula on its inner side. 



The furcula was much damaged. From the fragments 

 that I have been able to dissect out it can be seen that the 

 hypocleideum was extremely reduced. 



General Remarks on the Osteoloyical Characters of 

 Zeledonia and the Turdidse. 



That in general conformation the skull of Zeledonia 

 resembles that of the Turdidae more closely than that of any 

 other family is clear. Furthermore, it would seem that 

 among the Turdidse Zeledonia must take its place with or 

 near the Sialiinaj : the likeness which the skull presents to 

 those of Sialia and Grandala, at least, seems to support this 

 view. Unfortunately I have but a damaged skull of Gran- 

 dala coelicolor, and this is too much broken to admit of a 

 comparison of the tympanic region. 



Probably these small forms, and with them the equally 

 diminutive members of the Ruticillinse and Saxicolinae, 

 should be regarded as more primitive than the typical 

 Thrushes, such as Geocichla, Turdus, Merula, &c. The 

 forms of the external auditory meatus (ty mpanic cavity) and 

 of the palato-pterygoid articulation both point in this 

 direction. In Zeledonia the tympanic cavity seems to be 

 of a very simple type, and this, coupled with the large size 

 of the hemipterygoid element of the palatine and the non- 

 pneumaticity of the skull, would seem to indicate that 

 Zeledonia is one of the lowest members of the Turdiformes. 



