VEETEBEATES. 209 



imperfect state of preservation. A nearly perfect mandibular tooth, 

 save for the mutilation of the outer posterior angle, from the Lower 

 Burlington limestone, may not be distinguishable from less perfect 

 specimens from the main fish-bed of the Upper Burlington in which 

 occur the maxillary teeth described. The almost quadrangular shape 

 of the form and its proportionately narrower transverse diameter are 

 the only apparent characters inconsistent with their association with 

 the typical example of the supposed maxillary form above noticed. 

 The same horizon in the Upper Burlington limestone at Quincy, 

 however, has afforded Professor Worthen a unique specimen of a 

 tooth referable to the same form, which is distinguished by its nar- 

 row lateral diameter and more quadrangular outline, which, together 

 with the course of the anterior and posterior margins, strikingly re- 

 semble the opposed form mentioned above ; its transversely depressed 

 coronal surface, however, clearly discloses its homological identity 

 with the supposed maxillary form. Greater or less variability in the 

 proportions of these teeth may be readily anticipated, and the latter 

 example may be merely an unusually elongate tooth of the same 

 species as that regarded as the type of the species, first described 

 above. However, should this supposition prove to be erroneous, the 

 last mentioned tooth would then be a unique representative of a 

 distinct species, while the narrow tooth would probably be identi- 

 fiable with the species to which the maxillary teeth described above 

 belong. 



The forms described differ in so marked a manner from those of 

 the previously described species, Psammodus Springeri, P. tumidus, 

 F. turyidus, as not to require special review of these distinctive fea- 

 tures. The maxillary form offers a typical example of the genus, 

 and which strongly resemble individuals of P. porosus, Agass. The 

 specific name is given in honor of Mr. James Love, of Burlington, 

 to whom we are indebted for many favors. 



Geological position and localities: Lower and Upper Burlington 

 limestone; Burlington, Iowa, and Qnincy, Illinois. 



PSAMMODUS GLYPTUS, St. J. and W. 



PI. XIV. Fig. 5, 6. 



There are two imperfect specimens of large-size teeth in the col- 

 lections representing opposed forms of the upper and lower jaws, 

 which are distinguished by the very slight longitudinal convexity and 

 by the following characteristics respectively: The form probably 



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