THE MICROS AURIAN FAMILY TUDITANID^. 10 1 



species is known. The elements of the anterior part of the skull are not preserved, 

 but they are indicated by the broken lines in the drawing (fig. 22, G). The nostrils are, 

 however, clearly indicated as bosses of shale. There is a mere fragment of the nasal 

 preserved posterior to the crack indicated by the transverse line in the drawing. 

 The frontal is elongate as in other species of the genus and forms the inner border of 

 the orbit. The parietal, as usual, is one of the larger bones of the skull roof and the 

 pineal foramen is inclosed in the median suture by the two parietal elements. The 

 pineal opening lies in the posterior half of the parietal. The postparietal is almost 

 square, being slightly elongate transversely, uniting laterally with the tabulare, with 

 which it forms the truncate table of the skull. The suture separating the tabulare 

 from the supratemporal is clearly distinct. Although such a position for the supra- 

 temporal is unusual it is not unique, since the same character has been observed in 

 Diceratosaurus Icevis Moodie, described elsewhere (p. 120) in this paper. The post- 

 frontal is rather small and it, together with the postorbital, forms the posterior 

 boundary of the orbit. The postorbital is truncate posteriorly and joins the tabu- 

 lare broadly. The supratemporal lies posterior to the postorbital and jugal and 

 borders the quadratojugal, which is an unusual condition, but what significance 

 the condition has remains to be determined. Posterior to the supratemporal lies 

 the squamosal, which forms the quadrate angle of the skull. The quadratojugal is 

 a small element and forms part of the lateral boundary of the skull. The jugal is a 

 large element and forms the entire lateral border of the orbit. There are no teeth 

 preserved on the fragment of the maxilla, but there are some impressions farther 

 forward which resemble the pleurodont denticles of the modern Amphibia. 



The scvilpture of the surface of the cranial bones consists of parallel ridges which 

 are separated by grooves equal to them in width. The ridges radiate inward on the 

 squamosals and frontals and outward on the supratemporals. They are somewhat 

 interrupted on the other skull elements. The right clavicle is ornamented with a 

 sculpture of similar radiating grooves and ridges. 



Cope described an atlas in connection with this skull, but I do not find it. The 

 slender impressions to the right of the clavicle may possibly represent ribs. They 

 are gently curved and truncate at the inner end. 



A nearly complete system of lateral-line canals has been detected on this skull. 

 The canals preserved are : the temporal, the jugal, the infraorbital, the occipital cross- 

 commissure, and the supraorbital. These terms were used for the first time for the 

 Amphibia by the writer (458) in a discussion of the organs and their significance in the 

 correlation of the skull elements. The occipital cross-commissure in the present 

 skull is represented by a row of elongate pits, such as Andrews (8) has described 

 for Ceraterpeton galvani Huxley from the Coal Measures of England. The cross- 

 commissure is contained within the tabulare. The jugal and temporal canals form 

 a complete ring, much as the same canals do in Trematosaurus. The supratemporal 

 in Erpetosaurus tabulatus Cope is excluded from the parietal by the extension of the 

 tabulare and the postorbital, and it is to be noticed that the temporal canal has a 

 changed position to correspond with the changed condition of the squamosal. This 

 is of considerable interest in connection with the correlation of the supratemporal 



