24 WATSON & Day, Notes on some Palaeozoic Fishes. 



firmly articulated with the maxilla at its thin 

 dentigerous edge. 

 (6) that in Glyptopomus there is a special foramen in 

 the palatine, which is not merely a space left 

 between two bones by imperfect ossification, but 

 lies entirely in one bone. This opening agrees 

 exactly with the internal naris of early Stegocephalia. 

 It is quite certain that a suggestion, which has 

 occurred to us, that it might possibly have served 

 to receive the tip of a large tusk in the lower jaw in 

 the way that an analogous foramen does in certain 

 Stegocephalia, is incorrect, because it is far too large, 

 there is no tooth in it, and there is no tooth in the 

 lower jaw for it to receive. We leave to another 

 occasion all discussion of the extremely important 

 morphological questions raised by the occurence, in 

 fish, of an external nostril lying above the junction 

 of the maxilla and pre-maxilla, which is shown in 

 our material of RJiizodopsis and even more clearly 

 in Megalichthys material with which we are not 

 concerned, and of internal nares on the palate, 

 shown so clearly in our specimen of Glyptopomus. 

 We are glad to be able to confirm Dr. Traquair's 

 description of a hyomandibular in RJiizodopsis. The 

 very slight ossification of this element and the fact that it 

 is apparently divided into two are of considerable im- 

 portance, and the presence of a quite large foramen 

 piercing its upper end is of still greater interest, for such 

 a foramen is known in few fish and is a common feature 

 in the stapes of early Amphibia and Reptilia. 



Another interesting feature, so far as we know hitherto 

 undescribed, is the occurrence of the spines or free scales 

 associated with the pelvic fins which we have found in 

 Gyroptychius and RJiizodopsis. It is not impossible that 



