334 Prof. D. M. S. Watson on 



jaw and visceral arches, wliicli we have seen to beneoniorphs 

 without morphological importance. At tlie same time, I think 

 it probable that we have in Mucropoma the beginning of the 

 process which results in Teleosts in the production of an 

 anto- and a dermo-palatine : ail I wish to make clear is that 

 the palatine of Ccelacauths is not to be regarded as a)i original 

 ossitication in the palato-qnadrate cartihige. 



Tlie so-called pre ethnioid of Coelacanths reseml)les in 

 structure the palatine, with which it articulates, and, like that 

 bone, supports a tooth-plate. In position on the palate and 

 in the associated teeth it recalls the prevomer of an Osteolepid. 

 I am extremely doubtful of its being an ossitication on the 

 nasal capsule, and prefer to regard it as a prevomer, fully 

 recognizing that it is very unusual in passing on to the 

 dorsal surface of the parasphenoid, in extending so far 

 dorsally over the side of the olfactory capsule, and in its 

 perforation by a foramen. 



The ectopterygoid is identified without difficulty. 



The accurate determination of the homologies of the dermal 

 bones of the outer surface of the head in Coelacanths seems 

 to me at present impossible. Only in Osteolepis, Megalichthys, 

 Eust/ienopteron, and Dictyonosteus is the struciuie of the 

 snout known at all. In Osteolepis and Meyalichtht/s, where 

 I have been able to examine considerable numbers of good 

 sj)ecimens, the number and arrangement of the bones in the 

 anterior region of the skull vary enormously ; in the latter 

 genus especially they are seldom synimetrical, and I prefer 

 not to attach independent names to them. 



The skull of Eusthenopteron represented in Stensio's tig. 57 

 differs very greatly from Bryant's restoration, which is bi^rne 

 out by his phologiaj)hic plates, and in the passage of the 

 supratemporal cross-commissure of the lateral line apparatus 

 over the tabulare and interparietal ditt'ers from all Usleolepid 

 skulls I have ever examined. 



MacropoDia clearly presents a multiplication of dermal 

 bones, and is not a favourable subject for study ; but I think 

 it probable that the peculiar bonew^ith a downwardly directed 

 process and the second j)aired parafrontal are separated parts 

 of IStensio's nasalo-antorbital, and that the process separated 

 the two narial apertures. 



One of the most sti iking characters of the Coelacanth skull 

 is tiie hinge between the parietals and frontals, which is in 

 Macropoma continued outwards between bones of the para- 

 Irontal series. 



Tliis hinge is exactly similar to that which occurs in an 



