. Carnegie Institution of Washington publication. TRIONYCHID/K. •W5 the ridge on the lower surface, is 16 mm. Where it made contact with the preneural the thickness is only 4. mm. The portion of" the costal, the proximal halt", almost certainly belongs to the same indi- vidual. At its proximal end it presents the sutural borders for the preneural and the first neural. Evidently the preneural was somewhat wider than the neural. Its length was at least 40 mm. The border of the costal for union with the neural is 7 mm. thick. About the middle of the length of the hinder border of the co
. Carnegie Institution of Washington publication. TRIONYCHID/K. •W5 the ridge on the lower surface, is 16 mm. Where it made contact with the preneural the thickness is only 4. mm. The portion of" the costal, the proximal halt", almost certainly belongs to the same indi- vidual. At its proximal end it presents the sutural borders for the preneural and the first neural. Evidently the preneural was somewhat wider than the neural. Its length was at least 40 mm. The border of the costal for union with the neural is 7 mm. thick. About the middle of the length of the hinder border of the costal the thickness is 7 mm. The upper surface of the bone is incrusted with a layer of iron oxide ; but so far as can be discovered the sculpture was finer than in the other two species found in that region, ./. austerus and A. vorax. The few pits observed appear to be about mm. in diameter. The respects in which this species differs from those just named are mentioned under their respective descriptions. Aspideretes austerus sp. nov. Text-figs. 649, 650. The fragmentary specimen on which the present species is based was collected in 1904, by Mr. Barnum Brown, from Laramie deposits at OjoAlamo, San Juan County, New Mexico. The catalog number of the specimen is 6068. The remains, belonging apparently to a single individual, consist of the nuchal except the central portion, part of both first costals, the greater part of a right posterior costal, probably the sixth, various fragments of costals, a piece furnishing parts of two neurals, and a considerable portion of the right hvpoplastron. The species is characterized by the very thick bones and the coarse sculpture of both the carapace and the Fig. 649.—Aspideretes austerus. X I- Parts of nuchal and first costals of type. On account of the missing middle region of the nuchal, the exact lateral extent of this bone can not be determined. It was, however, not far from 230 mm., being thus somewhat less than that of
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