Rev. T. Hincks on British Pulyzoa. 521 



The opinions of so learned and able an investigator are en- 

 titled to the most respectful consideration, and properly carry 

 very great weight with them. No doubt many points may 

 be urged in support of the position which he has assumed ; 

 and these he has presented in his various works Avith much 

 force and ample illustration. But I have been unable to 

 satisfy myself that the extreme view which he adopts in refer- 

 ence to the colonial characters is philosophically just, or (con- 

 sequently) that the systematic method based upon it is likely 

 to yield a good practical result. As to the latter point, I 

 think I may appeal with some confidence to the writings of 

 Prof. Smitt himself. The agglomeration of diverse forms, 

 to which the application of his theoretic principle has in many 

 cases given rise, cannot certainly be regarded as natural^ and 

 may fairly be taken as a warning against the entire disregard 

 of colonial characteristics. 



After giving the subject the best consideration in my power, 

 it seems to me that to represent at all adequately what may 

 be called the family relationships of a tribe like the Polyzoa, 

 in which colonial life is all but universal, more or less account 

 must be taken of the two elements, the zoooecial and the colo- 

 nial, and that the circumstances of each case must decide what 

 amount of systematic significance shall be assigned to the 

 latter. I have no doubt that authors have commonly laid 

 undue stress on trifling variations in the mode of the colonial 

 growth, and have consequently multiplied genera needlessly, 

 and have at the same time obscured the natural relation- 

 ships. 



Another fruitful source of error has been the tendency to 

 make the mere habit of growth, apart from the characters 

 supplied by the structure of the cell, the basis of generic 

 groups. Thus the old genera Lepralia and Eschara are 

 miscellaneous assemblages of forms which have often little in 

 common but general habit. 



Between the two extremes, that of the older classification 

 and that which has found so able an advocate in Prof. Smitt, 

 the true systematic method must, I believe, be sought. The 

 position which I should adopt would be, that whilst the 

 zoocEcium is undoubtedly the most important and significant 

 element, the mode in which the cells arc combined, the facics 

 of the adult colony, is a ])oint that nnist be taken account of 

 in forming natural groui)s. In applying the principle here 



cable to the other divisions of the Polyzoa. In ilealinjr with the Cijc.lo- 

 stoniata, tor instance, the jrcneraare perforce t'onnded in ij-reat jiart on thp 

 mode in which tho colls are combined — on the colonial liabit. 



