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. ~ 
ge FIELD COLUMBIAN MusrkuM—GEOoLoecy, VOL. II. 
pterygoid articular surface reaches. to within about twenty-five milli- 
meters of the articular extremity. The inner border of the pit is 
produced forward for articulation, apparently, with the paroccipital. 
The two narrow, concave, articular surfaces for the squamosal and 
quadratojugal are separated by a narrow, non-articular ridge. They 
both extend very nearly to the cotylar surface of the bone. 
The ptervgoids articulate posteriorly by a deep, pit-like suture 
with the inner side of the distal extremity of the quadrate; the latter | 
does not send out a process to meet the bone. The bar connecting 
the quadrate with the body of the bone is oval in cross-section, with 
a rounded inferior border. It is about thirty millimeters in length 
and is placed obliquely; it does not extend much posteriorly to the 
coronal plane of the occipital condyle. In front of this quadrate 
process there is an elongate, flattened or concave plate, with nearly 
parallel sides, separated from the parasphenoid bya slender, elon- 
gated vacuity.* At the posterior extremity of this plate there is a nar- 
row bridge connection with the basisphenoid. The connecting suture 
is not determinable, so that one cannot say whether the two ptery- 
goids meet here 1n the middle, as in Peloneustes and Pliosaurus, or are 
separated, as in Pleszosaurus. In front of the interpterygoid vacuity 
the pterygoids unite with the parasphenoid broadly; here also the 
connecting suture cannot be determined. Opposite this connection 
exteriorly, the bone sends out a stout process for union with the ecto- 
pterygoid or transverse bone. Back of both of these, and on the inner 
side, near the margin of the vacuities above, there is the attachment 
of a stout epipterygord pillar, passing upward, and apparently a little 
inward to unite with the lower anterior part of the parietals, as 
already described: both extremities are tumid, and the connecting 
sutures cannot be determined. The rod is broken on both sides in 
the specimen near the parietal end, and, as preserved, is curved for- 
ward. It is oval in cross-section, with the greater diameter of about 
ten millimeters; the entire length is thirty millimeters. Anteriorly, 
the pterygoid sends a flattened process to meet the posterior extremity 
of the vomers; it is flattened and pointed. This process is gently 
expanded at each extremity, especially the proximal; it has a smooth, 
thin edge on each side, except at the distal end, where it meets its 
mate, suturally, in the middle. Between the.two processes there is 
an: élongate, oval vacuity, which is not filled by the ossified para- 
* Andrews calls this opening the posterior palatine vacuity or foramen; but ‘this term is more 
properly restricted to the opening between the palatine, pterygoids and maxille, corresponding to 
the posterior palatine foramina of mammals, and is thus used in the Chelonia—the sub- or infra- 
orbital vacuity of Andrews and other authors. 
