330 THE CANADIAN NATURALIST. [Vol. vi. 



* 

 I place this species doubtfully in this genus, because there is 



in the interior of the dorsal valve, a distinct muscular pit about one 

 line in front of the beak, which does not occur in either of the 

 other two species. In one well preserved specimen this scar is 

 distinctly seen to be divided into two, by a longitudinal ridge. It 

 may be that it represents the small anterior scar (c. fig. 2,) 

 which is certainly variable in form and perhaps, also, in position. 

 In 0. Canadensis, for instance, the scar, c, is sometimes a distinct 

 ovate pit, as shown in fig. 2, entirely separated from the two 

 larger scars, hh. In others all three are confluent, or at least in 

 contact, while in one specimen, c, is represented by two elongated 

 grooves, separated by a rounded ridge, extending backwards 

 between, hh. Some of the figures of the English species 0. 

 Davidsoni, seem to show that a pit, like that of 0. magnifica, 

 occurs in one of the valves of that species. 



0. magnijica occurs in the Black River formation, along with 

 0. Canadensis. 



A Question of Priority. 



About three weeks after the above genus was published, I 

 received a letter from Thos. Davidson, Esqr., F.R.S. Brighton, 

 England, informing me that it had been previously named, by 

 Prof Hall in a pamphlet of 5 pages, dated March, 1871. On 

 this subject I beg to make a few remarks. 



When I was appointed to the office I now hold, in 1856, Prof. 

 Hall was engaged on his 3rd vol, Pal. N.Y., which relates altogether 

 to the Upper Silurian fossils of the State of New York. Sir W. 

 E. Logan gave me to understand that I was not to describe any 

 Upper Silurian fossils until Prof. Hall should have completed his 

 volume. It was also understood, that I should not describe any 

 species which might occur in New York and not in Canada. To 

 do so was thou2;ht to be in the hi":hest desrree discourteous and un 

 fair. Species that were found in Canada I could describe, although 

 they might be known to occur in New York also. I have never once 

 transgressed these rules for sixteen years. I have compared a num- 

 ber of collections for parties living in New York but have always 

 declined to describe new species, although frequently urged to do so. 

 There is a person at this present time at work on N. Y. fossils, 

 and I have declined to give him any assistance. 



It appears that many years ago, Prof. Hall obtained from Gait, 

 a single specimen of the ventral valve of 0. Galtensis. This spe- 



