300 MR. G. A. BOTTLENGEB OX SOME CRANIAL [Apr. 2, 



istic of Thymallus. For this reason Coregonus is retained in the 

 Salmonidae and Thymallus is raised to family rank ; the author 

 adding that the ThymallidiB are further distinguished from the 

 Salmonidse by the presence of epipleurals and the greater deve- 

 lopment of the dorsal fin, many of the anterior rays of which are 

 unbranched. The last feature, by itself, is too trivial to be used 

 as a family character ; and the first characteristic is unfounded, 

 Salino and Coregonus having well-developed epipleurals. 



As to the condition of the parietal bones, it seems curious that 

 there should be divergence of opinion on a point so easy to 

 ascertain even in spirit-specimens. It is not stated to what 

 species of Coregonus the skull belongs on which Gill's observation 

 is based, but all the examples I have examined in the British 

 Museum, skeletons and alcoholics, of European and American 

 species of that genus, show the parietals fonning a more or less 

 extensive sutiu-e between the frontals and supraoccipital, as ascer- 

 tained by Cope. I am therefore at a loss to accouijt for Gill's 

 statement to the contrary. 



I have also examined Brachymystax, which, from its very small 

 scales combined with a small mouth, holds a position intermediate 

 between Sahno and Coregonus ; the supraoccipital separates the 

 parietals, as in Sahno. 



In his paper quoted above, Gill founds a subfamily, Stenodon- 

 tinse, in the family Salmonidse, for the curious genus Stenodus, 

 Rich. (Luciotrutta, Gthr.), without having been able, however, to 

 examine the skeleton. A large head of the " Inconnu," Stenodus 

 mackenzii, from the Mackenzie Eiver, was presented by Mr. "Walter 

 Gordon Ciunming to the Museum a few weeks ago, and I have had 

 it prepared as a skull in order to supplement this gap in our 

 knowledge of Sahnonoid osteology. This skidl is here figured. 



It will be seen that Gill's statement, " lower jaw articulating 

 with the quadrates behind the eyes," is not quite correct, the 

 articulation of the mandible falling below the posterior border of 

 the orbit, in this respect intermediate between Salmo and Coregonus. 

 The posterior process of the quadrate is very long and slender. 

 The supraorbital is very large and in contact with the postorbital. 

 But what is especially noteworthy is the condition of the supra- 

 occipital and parietals, the latter bones forming a very short 

 suture, separating the former from the frontals, a condition which 

 is, in fact, intermediate between the two types mentioned above. 

 On examining a smaller specimen of Stenodus mackenzii and a 

 specimen of the Russian S. leucichthys, I find no union whatever 

 between the parietals, and therefore the character to which Cope 

 and Gill have attached so great an importance falls to the ground. 



It must be remarked, however, that, as I have ascertained by 

 removing the parietals in specimens of Coregonus williamsotiii, the 

 supraoccipital joins the frontal. Therefore even in Coregonus and 

 Thymallus the relation is a widely different one from that obtained 

 in Cyprinoids and Characinoids, the apparent resemblance being 

 pierely due to the fact that in the Salmonoids in question the 



