1888.] PROCEEDINGS OF UNITED STATE* NATIONAL MUSEUM. 255 



ber, and may or may not leave a longitudinal, spindle-shaped foramen 

 between its upper margin and the united free upper border of the nasal 

 and frontal. (Fig. 1.) 



The remaining process is the descending process of the lachrymal, 

 and it is overlapped posteriorly at its middle by the pars-plana, but 

 reaches the infraorbital bar by the latter being bent at a sharp angle 

 upward to meet it. 



This process has a circular foramen in front which leads into its in- 

 ternal cavity, but for which I fail to find an exit or recognize the use of 

 to the bone unless it be a pneumatic opening. 



The wing of the ethmoid completely fills in the remainder of the an- 

 terior wall for the orbit, being impervious in all its parts. It is sepa- 

 rated from its fellow of the opposite side by a median superior area of 

 bone, concave on its posterior aspect. This is the mesethmoid, and is 

 perforated for the passage of the olfactory nerves, the entire wall of the 

 brain-case being open opposite it. It is evident that this latter arrange- 

 ment gives rise to a large subcircular foramen in each orbital wall at 

 the upper postero superior aspect, through which we may see into the 

 cavity of the brain-case. The optic foramen seems to be intact and 

 perfect in all cases. Beyond it there is another circular foramen about 

 the same size, which pierces the interorbital septum here — really a con- 

 cavity between the sloping walls of the pars-plana on one hand and the 

 lower portion of the anterior wall of the brain-case on the other. 



The quadrate has a form much the same as in birds generally, but the 

 mandibular facets at its foot are characteristic. The outer and oblong 

 one is placed obliquely, its anterior end being forward; the inner and 

 lower one, in addition to a facet which it has placed nearly in the hori- 

 zontal plane, has another which looks almost directly forward. This 

 latter one is transversely grooved for its entire length. Viewing this 

 skull from above, we find it marked by a shallow, median groove, being 

 deepest between the orbits. 



The luuiform, supraorbital, glandular depressions occupy the entire 

 upper free margins of these cavities, extending between the lacrymals 

 and upturned, pointed post-frontals. They are clean-cut and deep* 

 being of about an equal width throughout. 



Posteriorly the skull is smooth and rounded, in direct continuation of 

 a similar character of surface of the parietal region. It lacks all those 

 angular definitions of areas so prominent in the Alcidw and Urinatoridce. 



The crotaphyte fossas are lateral and very feebl}- pronounced. Seen 

 upon its under side, we at once discover that the skull of this Petrel 

 presents all the characters of a veritable Cecomorph, which it is. The 

 arrangement of the bones of the hard palate is essentially the same as 

 in the Loons, Auks, and Guillemots. We notice here, however, that in 

 this Petrel the palatines each present a convexity toward each other 

 opposite where they meet the maxillopalatines. These latter are thin, 

 firm plates of bone arranged as in the Auks or Gulls, with the excep- 



