316 W. D. Lang — Jurassic Pohjzoa. 



The first point, namely, the artificiality of the genera Stomato'pora 

 atid Prohosdna, has already been discussed by Gregory,^ who, while 

 admitting that the line which divides them is arbitrarily drawn, 

 since it is obvious that the forms constitute a natural series, main- 

 tfiins that, if this be done, the genera Berenicea, BeptomuUisparsa, 

 Idmonea, Diastopora, Entalophora, and Spiropora must for similar 

 reasons be merged. And since the retention of these genera is 

 convenient for working purposes, he leaves them as they are. 

 But he does not suggest, what the author believes to be the case, 

 that these ' genera ' are polyphyletic in origin, and that in some 

 cases a given species of Prohosdna may be at the head of a series 

 of forms, the simplest of which are undoubted Stomaiopora. 



In such a case the series would form a natural genus parallel 

 with, and having a common origin with, other series. These 

 would constitute new genera, starting from the point at which they 

 branched from the first series. 



Given sufficient material, such series can be found, and in one 

 or two cases have been found, by tracing the development of the 

 d liferent characters of a colony from the first zoo3cium, and by this 

 means finding genetic relationships. 



And this question of zoarial development leads to the second 

 proposition, namely, that the development of the colony is com- 

 parable with and follows the same laws as the development of the 

 individual. 



It was the observation of this fact that led the author to doubt 

 the validity of the ' genera ' under consideration, and the matter 

 was fully treated of in a paper. This paper, however, was not 

 published, because it was considered a poor thing to put forward 

 an idea having such a destructive tendency without providing an 

 alternative scheme whereby a natural classification could be con- 

 structed. And the latter would involve much further detailed work, 

 some of which has since been done. 



Cumings,- however, in January of this year, in a paper on the 

 development of Fenestella and other Palgeozoic forms, has in a 

 masterly manner shown tliat the zoarium has a developmental 

 history, exactly comparable with that of the individual. He says : ^ 

 '• The now generally accepted classification of the stages of growth 

 and decline, proposed by Alpheus Hyatt, has never been consistently 

 applied to a colonial organism, such as are the Bryozoa, nor to 

 one whose ontogeny presents the retrograde metamorphosis which 

 characterizes the latter class." He further proposes a nomenclature 

 for the stages in the development of the colony analogous to the 

 nepionic, neanic, ephebic, and gerontic, or the infantile, youthful, 

 mature, and old-age stages, proposed by Buckman & Bather* as 

 modifications of Hyatt's original terms for the individual. These 



1 J. W. Gregory: Brit. Mus. Cat. Jur. Bryozoa, 1896, pp. 14-22. 

 - E. E.. Cumiugs: Amer. Jouru. Sci., vol. xvii, pp. 49-7S. 

 ^ Cuming-s: op. cit., p. 50. 



* S. S. Buckman & F. A. Bather, "The terms of Auxoloo-y " : Zooglischer 

 Anzeiger, 1892, p. 421. 



