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Show 1904.] OSTEOLOGY OF THE ELOPIDjE AND ALBULIDAE. 55 in a forward direction ; and in Megcilops it has an inclination intermediate between that of Elops on the one hand and that of Albula on the other. The laterally-directed process of the ectopterygoid, which in Albula runs below the eyeball to meet the upper edge of the suborbital bones, is feebly suggested, in both Elops and Megalops, by a narrow, laterally projecting ledge of the ectopterygoid. The lateral temporal fossa is roofed over in Elops, Albula, and Bathythrissa, but in Megalops the lateral temporal groove is broad and shallow, and has no roof. The interorbital septum is completely bony in Albula, but it is largely membranous in the other genera under consideration. The eye-muscle canal has a posterior opening in Elops and Albula, but ends blindly in Bathythrissa, and is blind in one specimen of Megalops, although opening in the other two. The ethmoidal region is elongated in the Albulidae, but not in the Elopida?; and the palatine has two articulations, one in advance of the other, whereas the articular head is single in the Elopidfe. While in the Albulidae the ethmoidal rostrum projects in front of the mouth, in Elops, and more particularly in Megalops, the lower jaw projects in advance of the upper. The supratemporals in the Elopidfe are large, thin scales of bone, which meet in the dorsal median line of the head, without forming a suture; in the Albulidfe the supratemporal is more laterally placed, is smaller, and has more the ti'iradiate character so common among Malacopterygian fishes generally. The branchiostegal rays are 32-35 in Elops, 23-25 in Megalops, 15 in Albula, and 6 in Bathythrissa. The spicular bone present in addition to the true first pharyngobranchial in the Elopidfe, is wanting in the Albulidae. Remarks on the Morphology of the Skull in the Lower Teleostean Fishes generally. In this section of the paper are offered some remarks, generalisations, and criticisms of published accounts of the skulls of fishes, based mainly upon an examination of the following species. Most of the skulls were specially prepared for the purpose of this research, it being found that the skulls of fishes as ordinarily prepared do not lend themselves satisfactorily to such a detailed examination as that to which it was deemed desirable to submit them in the present inquiry. Elops saurus. Megalops cyprinoides. A Ibula conorhynchus. Bathythrissa dorsalis. Mor my r ops deliciosus. Petrocephalus ba.ne. Gymnarchus niloticus JVotopterus kapirat. Hyodon alosoides Arapaima gig as. Heterotis niloticus. Phractolcemus ansorgii. Chanos salmoneus. Chirocentrus dorab. Chatoessus erebi. Clupea jinta. Dussumieria acuta. Evgraulis encrasich olus. Osteoglossum leichardti. j Coilia nasus. |