PLATE VIII. 



PAGE . 

 Kg. 1. AGA53I20DU3 VARIABILIS 313 



View of specimen exhibiting the nearly complete dentition of one ramus, proba- 

 bly the left side of the mandible or lower jaw, reduced to two-thirds the nat- 

 ural size. Towards the anterior extremity of the specimen at a, series of 

 teeth are shown, which, from their reversed position, woald appear to have 

 formed part of the dental armature of the opposite ramus. Upper Coal 

 . Measures, Osage, Kausas. 



2 a, b. Views showing the posterior and anterior faces of a large, perfect tooth belong- 



ing to the median row of acuminate teeth of the right ramus. Upper Coal 

 Meas., Mills county, Iowa. 



3tt,6,c. Posterior and anterior faces, and outline from above, of a small worn tooth from 

 near the outer extremity of the same row. Same position and locality as the 

 preceding, and fiom which were obtained the specimens of the following 

 figures up to Fig. 21, so associated as to leave no room to doubt that they 

 formed part of the dental remains of one aud the same fish 



4a,b,c. Views of a medium sized tooth belonging to the median row of the left ramus, 

 showing the posterior aud anterior faces, and outline from above. The abra- 

 ded condition of. the crown indicates its position in the outer half of the row. 



5 a, b, c, d. Similar views and profile scetion of a small outer tooth of the same row. 



$a,b,c. Posterior aud anterior faces, and outline from above, of a specimen remarkable 

 for the eccentric position of the mediam prominence, and which may have 

 belonged to the median row of the right ramus of the upper jaw. 



7 a,b,c, d. Similar views, and profile section, of a large perfect tooth, probably belonging to 

 the first row anterior to the median row, the immature condition of the root 

 a,s well as the nnahradi-d state of the crown plainly iudicating its inner posi- 

 tion. Possibly pertaining to the Tipper jaw. 



3a,b,c,d. Similar view of a mature tooth of the first row anterior to the median row of 

 the left ramus of the mandible. 



9 a, 6, c. Views .showing the posterior and anterior faces, and outline from above, of a 

 mature, perfect tooth of the same ramus as the preceding, and probably be- 

 longing to one of the anterior rows. 



10 a, b, c. The same views of a small tooth, probably referab'e to one of the posterior rows 



of the same ramus. 



11 o, b, c. Similar views of a still smal er mature tooth, which probably belonged to one 



of the extreme posterior rows of the same ramus. 



12 a,b.c. Similar views of mature tooth, probably belonging to one of the anterior rows of 



the right ram us of the mandible. 



13 a, b, c. The same views of small tooth of one of the posterior rows of right ramus. 



14 a, &, c. Similar views of a very small tooth apparently belonging to one of the extreme 



anterior rows of the right ramus. 



15 a, b, c. Similar views of a tooth, probably belonging to one of the extreme posterior 



rows of the mamillaries, showing the crown at one extremity divided into two 

 minute secondary cones, which latter recall some of the entire teeth compos- 

 ing the extreme outer rows in front. 



16 a, b, c. Posterior, anterior, and profile views of a very small, irregularly-shaped, depres- 



sed tooth, possibly pertaining to the maxiilar/y, or upper jaw. 



17 a, b,c,d. Outline from above, natural size, and enlargements showing the posterior (?) and 



lateral faces of a minute cylindrical tooth, the continuation into the root res- 

 tored in outline. 

 16 a, 6, c Views of a minute, laterally compressed tooth, presenting the normal vertical 

 proportions peculiar to the form, showing the crown from above, lateral and 

 anterior aspects of lower jaw. 



19 a, b, c. Views, natural size and enlarged, from above, and lateral aspect, of an exceed- 



ingly minute tooth, in which the root is relatively very shallow and propor- 

 tionately broad anteroposteriorly. 



20 a, b. Views from above and posterior (?) face of a similar tooth to the last preceding, but 



laterally more elongated, with two distinct coronal promiuences rising from 

 the common basal support. Enlarged two diameters. 



21 a,b,c. Enlarged views exhibiting the external surface from above, a, theabrupt face 



and fore-shortened view of the shallow excavated inferior surface, &, and pro- 

 file, c, of a minute body supposed to pertain to the dermal covering of the 

 same fish to which the previously figured teeth belonged. These dermal or 

 shagreen scales are quite common and very varied in shape. 

 22. Restoration, showing the probable angle of divergence of the rami from the sym- 



physis in front posteriorly, and the convoluted or inrolled arrangement of the 

 rows of teeth, as indicated in the large specimen, Fig. 1. 



Fig. 23. AGASSI20DUS Virginiakus, St. J. and "W 321 



2-J a. View of the posterior face of nearly entire tooth, the lateral angles of the base 



restored in outline: b, anterior face, showing relatively shallow root ; c, view 

 of crown from above ; d, profile section. Position about 100 feet above the 

 Mahoning sandstone, near Morgantown, West Virginia. Coal Meas. 



