Cope.] u-ix [April 5, 



Thimeroruachis insignis. Gen. et sp. nov. Ganocephalorurn. 



See American Naturalist, May (April 22), 1878, p. 328. 



This genus is referred to the Cetnocephala of Owen, as a Stegocephal 

 Batrachian with vertebral centra represented by separate cortical ossifica- 

 tions, and with the chorda dorsalis persistent in the basioccipital region. 

 The basioccipital bone, although ossified, supports no condyles properly so 

 called, but a cup-like articulation for the first vertebra, like that of fishes, 

 but which is perforate for the chorda dorsalis. It possesses the other char- 

 acters of the suborder in the presence of zygapophyses and of the quadrato- 

 jugal arch. 



Char. Gen. The centrum is represented by three cortical ossifications of 

 the chorda-sheath, a median inferior, and two lateral. The lateral pieces 

 are quite distinct from each other, and are in contact with the neurapoph- 

 yses above, and the posterior border of the median segment in front. 

 The neural arch joins chiefly the lateral elements, but is in slight contact 

 with the lateral summits of the inferior element. The halves of the neural 

 arch are coossifiecl, and support well developed zygapophyses, but no neural 

 spine. A lateral expansion of the base of the neurapophyses represents the 

 diapophysis, but it is horizontal and thin. 



The cranial bones are sculptured with pits and reticulate ridges. The 

 parasphenoid bone is flat. The external nostrils are large and superior, 

 and not anterior. The angle of the mandible is little produced, and the 

 glenoid cavity is transverse and wider at the inner than the external ex- 

 tremity. The inner wall of the mandible descends from the glenoid fossa, 

 including with the horizontal outer wall, a deep internal pterygoid fossa. 

 No coronoid bone or process. Symphysis short. 



The teeth exhibit the inflected dentine of this and allied groups. So far 

 as preserved, they are simply conic, but there are none with the apices 

 complete. There are two series on each side of the upper jaw, both of 

 which consist of larger teeth at their anterior portions. The anterior teeth 

 of the inner row beneath the external nares, are much the largest. A thin 

 bilateral bone from some part of the roof of the mouth supports some large 

 teeth, and a row of small ones diverging from them on each side. The 

 mandibular teeth are in one principal series, and become a little larger an- 

 teriorly. Near the symphysis there are on each side, within the external 

 row, one or two large teeth. The ribs are short and little curved, and 

 they have flat expanded heads. They are attached to the diapophysial 

 expansion of the neural arch. Such limb bones as are preserved are with- 

 out condyles, and are of relatively small size. 



Trimerorhaehis differs from Archegosaurus in the ossification of the 

 basicranial elements ; in the absence of attached neural spines, and in the 

 regular and definite tripartite ossification of the chorda-sheath. The form 

 of the cranium of Trimerorhaehis is unknown. 



Char. Specif. There are two large tusks at the anterior extremity of 

 the inner superior row of teeth, and two similar ones on the plate-like ele- 

 ment above described. The inferior border of the mandible rises gradually 

 posteriorly to below the posterior border of the glenoid cavity, behind 





