on the Polyzoa. 85 



and extension of Smitt's system, which I have embodied in 

 my ' History ' of the British species. They take exception 

 at the same time to the importance assigned to the zooecial 

 orifice, which (they hold) is liable in many species to remark- 

 able variations and cannot be regarded as a stable character. 

 They say : — " Celui-ci (l'orifice zoecial) pre"sente dans beau- 

 conp d'especes des differences remarquables, et substituer line 

 classification base*e principalement sur le seul caractere de 

 cette ouverture a, celle qui avait principalement en vue la 

 forme de la colonie, c'est remplacer line classification arti- 

 ficielle par line autre, toujours moins eloigned de la realite. 

 On ignore encore quels sont les caracteres rdel lenient stables 

 dans les Cheilostomes aussi bien que dans les Cyclostomes "" *. 

 They add, " Dans ces derniers (Cyclostomes) presque tout 

 est encore a faire; dans les premiers, M. Hincks s'attache 

 presque exclusivement a la forme de l'orifice zoecial." 



Upon this I would remark that the latter statement can 

 hardly be accepted as a correct representation of the actual 

 fact. I have not relied by any means " exclusively " on the 

 form of the orifice in forming genera, nor has it been as a 

 matter of choice that I have in any case contented myself 

 with a single character ; much less can it be said with truth 

 that it has been my purpose to make the zooecial orifice, as a 

 substitute for the colonial form, the basis of my classification. 

 My primary object has been to give effect to the new syste- 

 matic principle in the best way which the actual state of our 

 knowledge loould permit ; and if in some cases the structure 

 of the zocecial orifice has been adopted singly as the basis of 

 generic groups, it is simply because, from the imperfection of 

 our knowledge, no other characters of equal stability and 

 significance could be found. I will reproduce here the 

 following passage from the u Introduction " to my ' History,' 

 which has reference to this subject : — " What, then, are the 

 most significant features of the zooscium for classificatory 

 purposes ? Form, superficial sculpture, the presence or 

 absence of spines or other appendages, these are generally 

 too variable and inconstant to yield any sure criteria. But 

 we may find such in the structural peculiarities of the cell — 

 as, for instance, the modifications of the aperture, the degree 

 in which the primitive opening is preserved or obliterated, 



* "La Faune des Bryozoaires Garumniens de Faxe," Ann. de la Soc. 

 Roy. Malacologique de Belgique, torn. xxi. (1886). Mr. Walford has 

 strangely misinterpreted the latter part of this passage and has given to 

 one of its clauses a meaning the very opposite of that which the authors 

 intended ; see his paper on " Bryozoa from the Inferior Oolite," Quart. 

 Journ. Geol. Soc. for August 1889. 



