84 Rev. T. Hincks's Critical Notes 



should rest not on mere superficial resemblances, but on 

 genetic affinity. 



The details of his classification — his definitions of genera, 

 his identifications of species, his grouping of varietal forms, 

 and other points — may be open in some cases to criticism 

 and revision ; but it may be safely affirmed that he has indi- 

 cated the direction which all sound and fruitful research must 

 take for the future *. 



Within the last few years there has been a very general 

 acceptance of Prof. Smitt's fundamental principle amongst 

 students of the Polyzoa, though there are still serious diver- 

 sities of opinion as to the zocecial elements which possess the 

 highest systematic value, and we must await the results of 

 yet further investigation before we may hope to realize a 

 perfect system. In the meantime it may be useful to indi- 

 cate the nature and scope of some of the differences which 

 exist amongst writers on the Polyzoa, and endeavour to esti- 

 mate our actual position with reference to systematic questions. 

 Amongst those who in recent times have occupied them- 

 selves with these questions I may name Jullienf, Koschinsky J, 

 and Pergens and Meunier §. Waters too, in his numerous 

 papers (chiefly on fossil forms) and in his supplementary 

 notes on the ' Challenger ' Polyzoa, has given us many inter- 

 esting suggestions bearing on systematic points which merit 

 careful consideration. To some of these 1 hope to refer here- 

 after. 



All these writers are agreed in seeking the basis of classi- 

 fication amongst the characters of the zocecium, so far at least 

 as the Cheilostomata are concerned. Pergens and Meunier 

 adopt in great part, though only provisionally, the revision 



* It must be remarked here that Smitt did not carry out bis principle 

 in the arrangement of the Cyclottomata. He says, " Formse vero Cyclo- 

 6tomatum sicut in antiquionbus geologise temporibus maxime floruerunt, 

 sic etiam inferiorem evolutionis gradum retinuerunt, ita ut, quamvis variis 

 fiouris coloniarum abundet hie ordo, zooecia fere aequalia pra^beat " (" Bryo- 

 zoa Marina in regionibus arcticis et borealibus viventia," Ofversigt af 

 Kongl. Vetensk.-Akad. Forkandl. 1867, no. 6, p. 467. 



f "Note sur une nouvelle division des Bryozoaires Cheilostomiens," 

 Bulletin de la Soc. Zool. de France, t. vi. (1881) ; " Monographie des 

 Bryozoaires d'eau douce," ibid. t. x. (1885) ; " Les Costulidees, nouvelle 

 Famille de Bryozoaires," ibid. t. xi. (1886) ; ' Mission du Cap Horn, Bryo- 

 zoaires.' 



% " Fin Beitrag zur Kenntniss der Bryozoen-Fauna der alteren Ter- 

 tiarschichten des siidlichen Bayerns," i. Abtbeil., Cbeilostomata. Palseon- 

 to°-raphica, herausgegeben von Karl A. von Zittel, Band xxxii. Erste Liefe- 

 rung, 1885. 



§ " La Fauue des Bryozoaires Garumniens de Faxe," Ann. de la Soc. 

 Malacologique de Belgique, torn. xxi. (1886) pp. 12, 13. 



