on the Polyzoa. 87 



opening as a generic distinction and gives it a prominent 

 place in his diagnosis. Koschinsky, in his very valuable 

 paper on the Cheilostomata, gives it as his opinion emphati- 

 cally that the form of the orifice is one of the most constant 

 and available characters for classificatory purposes : — " Sehen 

 wir von diesen und einigen anderen Fallen ab, so enveist sich 

 die Form der Mundoffnung immerhin als eine der constant- 

 esten und brauchbarsten Merkmale " (op. cit. p. 9). Waters 

 (Supplementary ' Challenger ' Report, p. 3) has the fol- 

 lowing : — " Much has lately been written about classification, 

 and some very unfortunate and premature attempts have been 

 made at remodelling ; established genera have been rechrist- 

 ened, and generic names given where it has been doubtful if 



specific were required As to my own position, I have 



repeatedly stated that, as far as the Cheilostomata are con- 

 cerned, I consider an immense advance was made when the 

 zooecial characters were put in the first rank, and believe that 

 we are upon the right track ; but none of us can suppose that 

 there will not be much to alter as new facts are brought to 

 light." I quite concur in these remarks. We are feeling 

 our way as yet ; but I believe, with Mr. Waters, that (i we 

 are on the right track,'' and that we shall more surely reach 

 our goal by the patient accumulation of facts and the careful 

 study of their significance than by premature and revolu- 

 tionary change. 



I have already quoted the passage in which Pergens and 

 Meunier refer to the variability of the orifice in many species, 

 and have pointed out the error into which they have fallen in 

 supposing that there has been any intention of substituting 

 a single-character classification of any kind for the old system 

 founded on colonial form *. 



As to the alleged variability, there are no doubt cases in 

 which differences of greater or less importance occur within 

 the limits of a species. Some of these I have already pointed 

 out elsewhere ; but, so far as my experience goes, there is 

 nothing exceptional in the amount of variability which occurs 



* Jullien also implies that the classification adopted by Smitt and (with 

 modifications) by myself rests on "the form of the orifice" ('Notesur 

 une nouvelle division des Bryozoaires Cheilostomiens,' p. 2). It does, of 

 course, rest in part on this character and on the general structure of the 

 orifice, but by no means as a whole. We have recognized a high signifi- 

 cance in this character, but we have never proposed, so far as I know, 

 to imitate the error of the older systematists, and base our system on a 

 single structural feature. In a certain number of genera undoubtedly it 

 has been made the diagnostic : but this, as I have already explained, is 

 simply because no other character of equal significance, or, indeed, of any 

 special significance at all, could be found at the time. 



