OBSERVATIONS AND QUERIES. 117 



gives, in his "Key to North American Birds," the following rule for their 

 employment : — " We treat as 'specific ' any form, however little different from 

 the next, that we do not know or believe to intergrade with the next one, — 

 between which and the next one no intermediate equivocal specimens are 

 forthcoming, and none, consequently, are supposed to exist. This is to imply 

 that the differentiation is accomplished, the links are lost, and the characters 

 actually become ' specific' We treat as varietal of each other any forms, 

 however different in their extreme manifestation, which we know to inter- 

 grade, having the intermediate specimens before us, or which we believe, with 

 any good reason, do intergrade. If the links still exist, the differentiation ig 

 still incomplete, and the characters are not specific, but only varietal, in the 

 literal sense of these terms. In the latter case, the oldest name is retained as 

 the specific one, and to it is appended the varietal designation." Dr. Coues 

 finds himself obliged to admit that "no infallible rule can be laid down for 

 determining what shall be held to be a species, what a con-species, sub- 

 species, or variety. It is a matter of tact and experience." In accordance 

 with the view of a sub-species expressed above, Dr. Stejneger, in 1886, 

 separated our Marsh Titmouse under the name of Parus palustris dresseri* 

 Now, without committing myself to a definite answer to Mr. Swann's question 

 as to the specific validity, or otherwise, of our bird, I will say that at 

 present it seems to be wisest to regard it as a local variety of the Continental 

 bird, but if it should turn out that our bird does difftr constantly from that 

 of the Continent, then of course it will be entitled to specific rank, and 

 should receive a name accordingly. In July, 1894, a meetiog (called at 

 the instance of Dr. R. Bowdler Sharpe) was held at the British Museum, 

 •whereat Dr. Coues was invited to meet a number of British naturalists to 

 consider whether it was expedient to adopt trinomial nomenclature in 

 Zoology. A report of the meeting will be found in " Nature " for that year 

 (vol. xxx.) It will suffice here to say that the views of the American 

 Zoologist on this subject met with very qualified approbation. — W. C. J. 

 Buskin Butteefield (St. Leonard's-on-Sea). 



The quotation from Dr. Coues's " Key " almost expresses my view of the 

 matter, and is again synonymous with Canon XI. of the A.O.U. Code. I 

 am, however, inclined to disagree with the rather strained application of the 

 rule indicated, which confers binomials upon what are really poor sub-species 

 merely because intermediate forms, although suspected to exist, do not 

 happen to have been proved to do so ; several cases of this occur in the new 

 A.O.U. Check List (for instance, No. 282, Macrorhamplms sco/opaceus), and 

 it is a proceeding which I, for one, much regret. To return to P. palustris 

 dresseri, Mr. Butterfield seems to me to be quite at fault in his application 

 of the rule he cites. The British form of P. palustris is decidedly merely a 



