124 BULLETIN UNITED STATES GEOLOGICAL SUEVEY. [VoLYI. 



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 lachrymal ; 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 i^resents 

 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 tymiianic. 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 j^late, that j^oints 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, x^laced vertically. The inner portion consists of a square 

 lamina of bone, looking upwards and forwards ; the other smaller and 

 outer portion is a trihedral 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 IStrigidce. 



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 

 tympanic, pterygoid, slightly by the lachrymal, 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, im- 

 movable, with the maxillary and intermaxillary. Back from this point 

 as far as the under surface of the lachrymals, on either side, they are but 

 very slender, straight, and horizontally flattened 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 vertical plate for articulation with 

 the fan-like and anterior ends of the pterygoids, while mesially they de- 



