BRITISH FOSSIL CRETACEOUS BIRDS. 499 



frontal, which it obliquely overlapped. The parietal appears to 

 have been prolonged further forward in the line of the median crest 

 than is evidenced by the preservation of the bones. The bones are 

 transversely arched. 



The squamosal bone differs from that element in the Divers, Cor- 

 morants, and Grebes (which in general form of cranium approximate 

 to the fossil) in being folded so as to form a narrow inferior surface 

 more than ^ inch wide and about -| inchlong, and a superior tri- 

 angular, somewhat Y-shaped area fully j inch deep and as wide. 

 In this folded character there is some approximation to the condition 

 of the squamosal bone in the Goose tribe. 



The occipital crest seems to have been well elevated. It is sinuous 

 and curves forward laterally, as in the Diver, but is more elevated 

 inferiorly than in that type, and has the articulation for the qua- 

 drate bone placed entirely behind it, which is not the case in the 

 Diver. The occipital aspect of the fossil is wonderfully like that of 

 Culymhus, and differs chiefly in the fossil being somewhat broader, 

 owing to the two sides of the occipital crest making a greater angle 

 with each other. The basioccipital articular condyle in the fossil is 

 probably removed by fracture. The Diver has the bone in front of 

 the condyle vertically compressed ; but in the fossil the basioccipital 

 was compressed even more, since the fracture has left but a narrow 

 rim to the base of the foramen magnum. The foramen magnum is 

 vertically ovate, and relatively rather larger than in the Diver ; it 

 is -§ inch high, and ~ 5 g- inch broad ; its upper border considerably 

 overhangs the base. 



The tympanic area is large, internal to the articulation for the 

 quadrate bone, and is best exposed in lateral view. It is limited 

 by four irregular sides, and has an irregular surface in which are 

 several perforations. The basitemporal bones, which are missing, 

 were shaped as in birds. The remarkable short-triangular form of the 

 base of the sphenoid may result from abrasion. It is broader than 

 in water-birds, but is essentially a modification of the sphenoid of 

 the Diver. As preserved, it is ^ inch long and y 5 -^ inch wide at the 

 base. This specimen I regard as the skull of Enaliomis Barretti. 



Another specimen, in the collection of Mr. Reed, at York, probably 

 belongs to another species. 



A fragment which I regarded in 1871 as a premaxillary of a 

 Toothless Pterodactyle has perhaps an equally good claim to be con- 

 sidered a portion of a premaxillary bone of a bird. It has already 

 been figured by Prof. Owen as the proximal end of the metacarpal 

 of the wing-finger of an Ornithosaur *. I have suggested for 

 it (Ann. Xat. Hist. January 1871, p. 35) the name Ornithostoma ; 

 for, if a bird-bone, it has nothing in common with Enaliomis ; and if 

 an Ornithosaur, the namewill be appropriate. It has thebase flattened, 

 concave from side to side, marked with blood-vessels, and tei urinating 

 laterally in well-defined ridges gently rounded, which are concave 

 in outline from front to back, so as to make the back wider than the 

 front. If the specimen should hereafter prove to be a j*w, this 

 * Pal. Soc. 1859, pi. 4. figs. 4 5. 



