52 



DR. AV. G. RIDEAYOOD ON THE CRANIAL 



[May 3, 



branchial is peculiar, the upright limb being exaggerated, and 

 the forward one reduced to such an extent that not only does it 

 fail to run along the mesial edge of the second pharyngobranchial, 

 but it does not even touch it. 



Te.xt-fip-. 18. 



AlhuJa conorhynclivs, liyobraiichial skeleton, dorsal view. The epibranchials 

 and pharyngobrancliials of the right side are not shown. For explanation of 

 lettering, see p. 81. 



Bathythrissa dorsalis (Pterothrissus gisu). 



I am pleased to be able to confirm a suggestion made by 

 Boulenger (" Revision of the Mormyridse," Proc. Zool. Soc. 1898, 

 p. 776) that Bathythrissa is not intimately related with the 

 Salmonidse, with which family Giinther had associated it (Ann. 

 & Mag. Nat. Hist. (4) xx. p. 443 ; Chall. Rep. Deep-Sea Fishes, 

 p. 221), nor with the Clupeidse, with which family Gill grouped 

 it (Mem. Is\at. Acad. Sci. Wash. vi. 1893, p. 131), but is nearly 

 allied to Alhula. Smith Woodward is evidently of the same 

 opinion as Bovilenger, for in placing the genus Istieus in the 

 family Albulidse, he remarks that Bathythrissa is not clearly dis- 

 tinguished from Istieus (Brit. Mus. Cat. Foss. Fishes, iv. 1901, 

 p. 67, also Introduction, p. vii). 



The posterior temporal fossfe are completely roofed over, as in 

 Alhula, but the lateral temporal fossae "are much shallower. The 

 relations of . the opisthotic, parietal, and supraoccipital are as in 

 Albula, except that the supraoccipital ctest is smaller. The basi-' 



