THE MICROSAURIAN FAMILY UROCORDYLILVE. 117 



normal form and only show an unusual difference in that they are large in the 

 inverse order. The pineal foramen lies in the anterior third of the parietals ; that is 

 the primitive condition which occurs in the young forms of the B ranch iosauridae. 

 The nostrils are inclosed by the premaxillae in front, in the median line by the nasals 

 and laterally by the maxilla?. The jugals, by their backward prolongation, form, 

 behind the maxillae, the border of the skull, and only attain to some size on the 

 upper side of the cranium. 



Jaekel's " perisquamosal " (see plate 15), which is of a doubtful nature, is not 

 indicated in the type specimen nor in the specimens of the other two species (462) 

 assigned to this genus. In D. robustns and D. ICEVIS the "perisquamosal" region is 

 easily separable into its component elements. The sutures between the elements 

 may have been indistinct in his specimen, but it is hardly conceivable that a union 

 of the skull bones would occur in one species and not in another of the same genus. 

 Jaekel's suggestion (347) that "Etwas mehr Wahrscheinlichkeit mochte ich der 

 Vorstellung beimessen, dass diese Ausbreitungen zum Schutz freier Kiemen dienten, 

 wie sie z. B. bei den Perennibranchiaten als baumformige Organe weit am Halse 

 herausragen" can hardly find acceptance with students of the Paleozoic Amphibia, 

 since there is not the slightest evidence that the Microsauria ever possessed external 

 gills and considerable presumptive evidence that they did not. His comparison 

 of the "perisquamosal" to the "Kiemendeckel" of the fishes is also very unhappy 

 on morphological grounds, since the elements of his "perisquamosal" form constit- 

 uent parts of the skull roof, which the operculum never does. 



The palate of the skull (plate 15, fig. 2) has been determined by removing the skull 

 bones of one specimen. Anteriorly the premaxillae and maxillae are clearly recogniz- 

 able as large dentiferous elements. The premaxillae have 4 to 7 teeth, the short max- 

 illa has 3 to 4. All the teeth are of nearly equal size. Smaller teeth seem to be 

 indicated by impressions found between the larger ones. The vomers, which are 

 tolerably large, unite with the premaxillae behind and inclose at least half of the 

 palatine foramen on the inner side. They are furnished with small teeth, which in 

 the anterior part are very irregularly placed, but they are more regular posteriorly. 



The palatines and transverse bones are questionably identified. They seem to 

 lie posterior and lateral to the vomers, but the sutures are indistinct. The large 

 parasphenoid seems well displayed and is more or less heart-shaped. There would 

 seem to be a slight indication of double occipital condyles. The pterygoids are 

 broad plates which inclose the parasphenoid and form the lateral boundary of the 

 palate. The cotyli are very indistinct, but appear as elongate grooves. 



The pectoral girdle (plate 15, fig. 3) consists, apparently, of seven elements, three 

 paired and one unpaired. The unpaired element (the interclavicle) is truncate pos- 

 teriorly and acuminate in front, with its surface radially grooved and the anterior 

 borders beveled for articulation with the clavicles. The clavicles are triangular, as is 

 usual with the Microsauria. They are sculptured with radiate grooves and ridges, 

 with decided inosculations at the ossific center. The coracoids have only part of 

 their surface ornamented ; most of their surface is smooth for articulation with the 

 interclavicle and scapula. A long spine projects from the inner surface of the cora- 



