422 Mr. H. Day on the 



scales, and the example from Ashton Moss Colliery is 

 associated with the disarticulated skuli-bones of a Palseonis- 

 coid fish, in association with scales which can be generically 

 identified as those of Rhadinichthys — probably R. monensis, 

 judging by the scale ornament. The second Pendleton 

 example exactly resembles the Ashton one, and probably 

 belongs to the same, or closely allied species. The three 

 specimens combined give an excellent idea of both dorsal and 

 ventral views of the bone. 



For convenience they will be described under the letters 

 A, B, and 0. A gives us a dorsal view of the bone ; B is in 

 part a ventral view, but anteriorly is merely cast; and C is 

 an almost perfect cast of the dorsal surface, and supple- 

 ments the facts observed in A. 



The bone consists essentially of a posterior rounded 

 expanded portion and an anterior rostrum or shaft. The 

 posterior portion possesses two pairs of lateral processes or 

 wings — an anterior pair situated at the junction of the shaft 

 and posterior expansion, and a posterior pair from the postero- 

 lateral margins of the expansion. 



Dorsal View. (Specimen A.) 



In the greater part of specimen A the actual bony 

 material is preserved, and an excellent view is given of the 

 main features of the dorsal surface. 



Anteriorly there is the long shaft which presents a rounded 

 convex surface to the observer (t. e., is dorsally convex). It 

 is constricted behind and expands anteriorly to give a slightly 

 club-shap'ed anterior extremity. The actual anterior extre- 

 mity in all three specimens exhibits distinct evidence of 

 having been forked, resembling in this respect the compound 

 para-basisphenoid of the common snake and the parasphenoid 

 of certain living and extinct Amphibia. 



The shaft, for its posterior two-thirds, is bounded by a 

 pair of wings closely applied to it. These wings are broad 

 behind, and, gradually tapering anteriorly, pass into the 

 shaft about one-third from its anterior extremity. Posteriorly 

 they pass into the broadened posterior part of the bone at 

 the point where the anterior pair of processes come off. 

 These wings, the bony material of which is actually pre- 

 served, each present a concavity to the observer (i. e., dorsally 

 concave) ; hence in specimens B and C, in which the shaft 

 and side-wings are represented as casts, we have the shaft 

 represented (except for adherent fragments of bone) as a 

 concavity to the observer, whilst the side-wings stand out 

 as convexities. 



