SHUFELDT. } OSTEOLOGY OF THE EREMOPHILA. 631 
latter is much smaller and quite circular; to its outer side there are 
several minute foramina that lead directly into the brain-case. The 
groove for the first pair is distinct anteriorly on either side, and opens 
into slits between the prefrontal and lacrymals, similar to those described 
when speaking of them in connection with the nasal cavities. These, 
the anterior rhinal foramina, together seem to be the homologue of the 
“cribriform plate” of anthropotomy. The anterior wall of an orbit is 
formed by a lacrymal; this bone is larger than usually found in avian 
crania of this size. It is quadrilateral in form, concave posteriorly, thor- 
oughly confluent with the frontal, nasal, and ethmoid, but not coming 
in contact either with the palatines or suborbital style. About the mid- 
dle of its outer border it presents a rounded notch for the lacrymal duct. 
Its anterior surface, forming the posterior wall for the rhinal vacuity, 
is undulating, though generally convex. 
The superior wall of the orbit is narrow, gently concave, and formed 
as usual by the frontal. It looks downwards and outwards and merges 
into the orbito-cranial septum behind, conformably with the shape of the 
cavity under consideration. The posterior wall of the orbit presents 
quite a number of interesting points for examination. Internally and 
above we find the posterior rhinal foramen, and below it the foramen 
opticus, already described. In addition to other minute openings men- 
tioned above, we have the foramen ovale, occupying a lower plane than 
any of the others, and situated more external to them, being almost di- 
rectly behind the orbital process of the tympanic. Above it we observe 
a thin circular convexity, indicating the locality of the mesencephalic 
fossa; this sometimes develops at its outer border a sharp, vertical, 
osseous spine or plate, that points downwards, forwards, and inwards 
into the orbital cavity. Still beyond this, outwardly, we find another 
process, or rather two processes combined, with an elliptical foramen 
between them, placed vertically. The inner portion consists of a square 
lamina of bone, looking upwards and forwards; the other smaller and 
outer portion is a trihbedral spine that descends, apparently from the 
frontal, to meet its external margin. The arrangement gives to the en- 
tire posterior wall a certain facing, directly forward, forcing upon the 
cranium of this little bird an aspect peculiar to another family, from 
which it is far removed—the Strigide. 
The osseous floor of the orbital cavity is always more or less imperfect 
throughout the class, and is here formed by the customary bones, the 
tympanie, pterygoid, slightly by the lacrymal, and limited externally 
by the malo-maxillary squamosal bar. ' 
The palatines nowhere come in contact with each other, and the pala- 
tine fissure is very wide, broadly rounded at both ends. The anterior 
extremity of each of these bones articulates in the usual manner, with 
the maxilliary and intermaxillary, the joints being immovable ones. 
Back from this point as far as the under surface of the lacrymals, on 
either side, they are but very slender, straight, and horizontally flat- 
tened little bones, without plate or process; at this latter point they 
suddenly expand into quadrate posterior ends, each slightly inclined 
downwards towards the median plane, throwing out a thin, nearly ver- 
tical plate for articulation with the fan-like and anterior ends of the 
pterygoids, while mesially they deyelop two other slender horizontal 
plates, the superior one being prolonged forward as a fine spicula of 
bone to meet the ethmo-turbinal mass, as above described. 
They lightly touch the rostrum of the sphenoid, in company with the 
pterygoids, forming the usual arthrodial joint at this point in avian 
structure. Above they are smooth, look upwards and outwards, and 
