352 BULLETIN UNITED STATES GEOLOGICAL SURVEY. [Vol. YI. 



the sutural traces are easily made out, and in cases where maceration 

 is persisted in, the coronal suture may gape — ^beyond, the interorbital 

 region becomes slightly depressed. The pseudo fron to -maxillary articu- 

 lation is denoted by a transverse line nearly a centimeter long, and is 

 moderately flexible; the superior tips of the lacrymals form its lateral 

 boundaries. The superior mandible is made up of the usual bones, it 

 is very broad at its base, and gently deflected throughout; the nasal 

 bones bound posteriorly on either side vacuities that lead into the rhinal 

 chambers, but the true nostrils are found beyond these, as distinct 

 elhptical aijertures. It is, however, the horny integumental sheath that 

 really gives to this bird's beak its peculiar raptorial aspect, for when 

 stripped of this, the osseous tomia show no sign of notch or tooth be- 

 yond. Below, the palatine fissure is quite wide, and through its open- 

 ing we discover that the ethmo-turbinals are more or less developed, 

 together with a partial septum uarium, and the space is farther intruded 

 upon by a sub-compressed and originally distinct vomer, that is bifur- 

 cated behind to receive the rostrum of the basi-pre-sphenoid, lodguig a 

 IDortion of the prefrontal in its fissure above. 



The palatines have become amalgamated with the inter-maxillary 

 anteriorly, and form, with the pterygoids, the usual joint on the rostrum 

 of the sphenoid behind ; they throw out sharp lateral apophyses that 

 are directed backwards. The pterygoids are very much expanded at 

 their mesial ends, their shafts being straight and delicate ; and there 

 are no pleurapophysial processes; they meet the tympanies in sub- 

 circular heads, of no great size, just below the orbital processes. These 

 latter elements possess very broad and twisted mastoid prolongations, 

 with the usual double facet and intervening depression below ; and the 

 orbital apophyses are pointed at their extremities, sometimes slightly 

 clubbed, being turned gently upwards. The segments composing the 

 infraorbital bar have long since become one single bone, a slender stylo 

 fulfilling its ordinary functions. A sub-elliptical sesamoid is found at 

 its proximal end, between it and the tympanic. The orbital cavities are 

 capacious, and well divided from the rhinal chambers by the broad, 

 quadrate lacrymals on either side ; their vaults are concavely arched, 

 and their posterior walls quite extensive, looking almost directly for- 

 wards. The foramen for the exit of the first pair from the brain-case 

 has run into one irregular aperture; but rarely joins, in the adult, with 

 the elliptical foramina for the optic nerves below them. The orbital 

 septum is never complete, a vacuity of greater or less extent occurring 

 near the center of the plate. Laterally we observe shallow temporal 

 fossie above elongated openings to the otocrane, that look downwards, 

 forwards, and outwards, standing out quite prominently from the side 

 of the skull. The mastoids throw forwards and downwards horizontally 

 flattened apophyses, which, by the aid of smaller ones from the ah- 

 sphenoids, help it to guide the temporal muscles to their points of 

 insertion. A moderately marked "cerebellar prominence" is found at 



