502 MR. A. SMITH WOODAVARD OX XIIE [Juiie 20, 



aspect" there is au undetermined amount o£ connection with some 

 of the ossified otic elements. The surface for articulation with 

 the upper extremity of thehyomandibular is clear, and a triangular 

 walled area at the hinder end of its inner face denotes the bound- 

 aries of the small temporal fossa. Postfrontal and prefrontal 

 membrane-bones are not differentiated from the cireumorbital 

 ring, and the cheek-plates are irregularly subdivided, being often 

 different even on the two sides of the same head. The general 

 plan of the cheelc-plates, however, is distinct, there being a complete 

 cireumorbital ring, a semicircle of postorbitals, and a short, deep 

 series of preorbitals flanking the ethmoid region^ The maxilla 

 (Plate XLIX. fig. 2) is a very delicate bone, deepest behind, 

 tapering forwards, and terminating in front iu an inwardly-directed 

 process for articulation with the palatine ; its oral margin is 

 provided with a series of styliform teeth. Th.e premaxUla (Plate 

 XLIX. figs. 1 c, 3) is a smaller, stouter bone, also with a single 

 series of styliform teeth, and bearing at its inner extremity a very 

 large ascending process which fits in a groove on the inferior 

 aspect of the frontal bones. 



The base of the cranium is sheathed by a great parasphenoid 

 bone and by the coalesced dentigerous vomers. Tha para-sphenoid 

 (fig. 3) is narrowest at the origin of the large, fan-shaped basi- 

 pterygoid processes (bpt.), expanding much behind and exhibiting 

 a deep cleft in its hinder margin. It is pierced mesially by a 

 foramen (/.) for the passage of the internal carotids, which appears 

 single on the lower face but double on emerging above; the 

 superior or attached face (fig. 3 a) also shows the deep excavation 

 forming the floor of the basicraniai canal. The vomer is a stout 

 thickened bone with crushing teeth, showing cavities in which the 

 germ-teeth are formed (Plate XLIX. fig. 4) ; and the dentigerous 

 bones of the palato-pterygoid arcade, closely connected with the 

 vomer in front, exhibit a similar thickening. 



The hyomandibtdar (Plate L. fig. 2) is an elongated, laterally 

 compressed bone, with its long axis slightly bent at the origin of 

 the process of support for the operculum {p.). It is somewhat 

 strengthened by longitudinal ridges on the outer face, and the 

 surface for attachment with the cranium is much extended. The 

 bone is not pierced by any foramen. The sijmplectic element 

 remains unknown, but the hinder border of the quadrate exhibits 

 an inner surface evidently for union with it. The quadrate (figs. 

 4 and 5) is slender for a fish with so powerful a dentition, and in 

 the fine example of Lepidotus latifrons from the Oxford Clay this 

 element is of much interest as exhibiting a very different degree of 

 ossification on the two sides. The metapteriigoid bone (fig. 6) is 

 also comparatively delicate, but it shows a broad facette on its 

 upward and anteriorly directed process, which may have articulated 

 with some lateral element of the cranium. 



The hinder portion of Meckel's cartilage is ossified as a robust 



' ?ep figures bj' Quenstedt, ojt. rif. 



