On the Cranial and other Skeletal Characters of Grandala ccelicolor, and its systematic position

SUMMARY. That Grandala is a true Thrush there can be no doubt, though in the matter of the form of the wing—that is to say of the length of the primaries in relation to the secondaries— it differs from all other Turdidæ. This, however, is an adaptive character. Its cranial characters must determine its systematic position, which is among the lower, less specialised members of the group in which Merula and Turdus seem to hold the highest place. That the form of the tympanic cavity will afford an important aid in determining the systematic position of this group in relation to allied groups seems certain from the results which have come to light during this brief investigation. It will probably prove no less valuable as a taxonomic factor within the group. It will probably be found that the several genera can be divided into two sections—A with a temporal fossa, and B with no temporal fossa. Section A will be further divided into (a) with a large bullate tympanic wing and circumaural groove associated with the superior tympanic recess, and ( b ) with the tympanic recess lacking a circumaural groove. Much material, however, will have to be collected before this suggestion can be put to the test, while a great deal of investigation needs to be done in regard to the nestling skull, since the relative contribution made to the formation of the “tympanic wing” by the squamosal and exoccipital respectively are by no means yet determinable. This point can only be settled by the examination of young skulls before the closure of the sutures.