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Show 1885.] OF THE HUMAN SPHENOID BONE. 585 lingulae of mammals. In the same specimen the basitemporal bones are present. The skull of this Ostrich is sufficient in itself to prove that the conclusions of Mr. Parker regarding the identity of the basitemporals of birds and the mammalian lingulae sphenoidale^ are based on erroneous premises. It now behoves me, seeing that I challenge these views, to identify the lingulae, and explain the apparently anomalous condition of the basitemporals. I shall address myself to the lingulae first. In the skull of certain fish there is a centre known as the sphenotic, which occupies the antero-external region of the periotic capsule, but the cartilage in which it arises is always of a composite character, being due to the confluence of proper cranial cartilage with that of the periotic cartilage. This centre is present in the Fowl in the very spot where the lingulae ought to be represented. In the chondro-eranium of Man, the cochlear region of the periotic capsule comes into union with the lingulae of the sphenoid, and the remains of the uniting cartilage are familiar to students of human anatomy as the cartilage filling up the foramen lacerum medium. If the cartilaginous lingulae of the bird and man are homologous, and on that score there can be no doubt, then the ossific nuclei which transform them into bone should certainly be considered homologous also. On these grounds m y contention is, that the nuclei called sphenotic in the Fowl and Ostrich are the true morphological representatives of the human lingulae. It is now necessary to find out to what ossifications in the mammalian skull the basitemporals of the bird really correspond. Turn from the Bird for a brief space, and inspect the hard palate of a Crocodile. From before backwards we find the following bones : - premaxilla, prepalatine portion of the maxilla, palate, and a bone usually marked pterygoid ; passing from the outer edge of this bone to the maxilla is a bony bar known to anatomists as the os transver-sum, the general relations of which can be readily seen by reference to Plate X X X V . fig. 4. The anatomical relations of the bone marked pterygoid are important in the following particulars : they surround the posterior nares, it being due to their intervention that the nasal passages are prolonged posteriorly to such a marked extent in the Crocodile. Above, they have the Eustachian passages, and externally they support the os transversum. This latter bone ought to be really regarded as the pterygoid. In Man's skull, and it is most probably true of other mammals, the internal pterygoid arises as an ossification of the distal end of the palato-pterygoid cartilage. The bone in the Crocodile's hard palate marked pterygoid arises as a membrane-bone, and during its growth the outer end invades to a slight extent the middle portion of the palato-pterygoid cartilage, and thus cuts off the distal end of the chondral rod, which becomes the os transversum, really the internal pterygoid. Even at the risk of being tedious I must make myself clear on this point In M a n a rod of hyaline cartilage stretches from, and is continuous with, the malleus at the eighth week of intra-uterine life ; it |
