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Show 3 6 UR. W. G. RIDEWOOD OX THE CRANIAL [May 3, suggestions and advice from Dr. A. Smith Woodward, Mr. G. A. Boulenger, and Mr. C. Tate Regan at the British Museum (Natural History). The mode of disarticulation and preparation of the skull adopted for the purpose of the present inquiry may be recommended for general rise. It is obvious that the skulls of Teleostean fishes, prepared as one now finds them in museums without the disarticulation of any of the parts, are unsatisfactory, by reason of the impossibility of studying minutely any but the most superficial bones. On the other hand, the maceration of the skulls until all the bones fall apart is equally open to objection, since, if the bones are stored loosely in a box, a great deal of time is wasted in sorting out the parts for study; while if the bones are wired at a, little distance from one another in the manner introduced by Owen, the mounted skull is unnecessarily bulky, and there is always the possibility of error in the process of rearticulation; and the expense is so great as to prevent the general adoption of the method. If, however, the skull be disarticulated into four parts as described below, the whole of the bones of the skull can be studied closely, the skull when stored occupies no more room than if no disarticulation had been made; the several parts can be rapidly placed in position for studying their mutual relations, and there is no possibility of erroneous rearticulation. From the fresh head, or one preserved in spirit, the nasal *, lachrymal, circumorbital, premaxillary, and maxillary bones of the left side are removed in one piece, and are carefully cleaned in such a way as to prevent their coming apart. The left palatine and left hyomandibular are then disarticulated from the cranium, the mandibular symphysis is severed, the left interhyal bone is disarticulated from the hyomandibular, and the whole hyoman-dibular- palatine arch of the left side, together with the left ramus of the mandible and the opercular bones of the left side, are removed in one piece, and are prepared without further dissociation. The whole hyobranchial skeleton (with the exception of the hyomandibular and symplectic bones) is then removed and prepared in one piece. The remainder of the skull is prepared in one piece : it exhibits all the bones of the right side in their undisturbed relations, and at the same time presents a freely exposed left view of the cranium. It has been found convenient to consider the constituent parts of the skull grouped as follows: (1) Cranium.- The term Cranium, as applied here, is a convenient appellation for that complex of not readily separable bones disposed around the brain. It includes the vomer and para-sphenoid, belonging strictly to the buccal series, and in some cases (e. g. Osteoglossum) the nasal bones. (2) Temporal and Preopercular Series.-Post-temporal, supra-temporal, subtemporal, preopercular, interopercular. The post- * In such skulls as those of the Osteoglossidae the nasal is not removed with this series, but is left with the cranium. |