EXPLANATION OF PLATES. 



PLATE I. 

 Sylkemus latifrons Cope. 



Figure 1. Provisional diagram of head, natural size, showing approxi- 

 mate arrangement of the bones visible from above. (See com- 

 ments on same, under Remarks on the species, page 30.) Ex- 

 planation of reference letters in the figure: so. supraoccipital; 

 i-so, interparietal portion of supraoccipital; p, parietal; epo, 

 epiotic; pto, pterotic; sph, sphenotic; /, frontal; me* mesethmoid; 

 pe, parethmoid; vix, maxillary; pinx, premaxillary; op, upper 

 part of opercular apparatus. 



Figure 2. Anterior border of premaxillaries, enlarged, showing three 

 of the teeth. 



Figure 3. Plan of the dorsal fin, natural size. 



Figure 4. Elevation of the dorsal fin, natural size; the posterior part 

 restored in supposed approximate outline, the anterior lobe drawn 

 from an imprint which is practically complete in the specimen, 

 lacking only a narrow zone at base. 



Figure 5. A group of scale-prints, across the lateral line, natural size. 



Figure 6. Caudal fin, natural size, the outline in part restored; made 



from a considerable part of the fin and an imprint of most of the 



remainder. 



♦This lettering, wliich refers to the median shaded bone iu advance of the 

 frontalt;. has been accidentally omitted from the i)late. 



PLATE IL 



Figure 1. Greater portion of lateral view of head of Pelecorapis varius 

 Cope, natural size. This and the following figure have been 

 drawn by Mrs. Dr. J. C. Shedd, after sketches by F. W. Cragin. 



Figure 2. Inferior side of left pelvic bone of Pelecorapis varius, re- 

 stored, natural size; the restoration based on a right and left in 

 the Wait specimen and a right in the Allen; with base of fin. 



Figure 3. Scales from mid-flank of Pelecorapis viicrolepis, sp. nov.; 

 enlarged to natural size from the Blackman photograph. See 

 Plate IIL 



PLATE in. 



Type-specimen of Pelecorapis microlepis, sp. nov., one-half natural 

 size. From a photograph by Mr. Albert A. Blackman. 



[Note. —The writer takes this opportunity to make an acknowledg- 

 ment, omitted by oversight from Volume VIII of the Studies. 

 The three figures of Sphenodiscus serpentinus in that volume 

 (Plate II, tigs. 4 to G) are from drawings very kindly made in 1897 

 by Mr. Robert T. Walker, Ph. B., of the Colorado College class 

 of 1900.1 



