90 Kev. T. Hincks's Critical Notes 



such cases will be largely tentative in character. The full 

 consequences of a new principle are not apprehended all at 

 once, nor is it easy to cast off on the instant the yoke of old 

 opinions, even when their foundations are shaken. All this 

 is in the order of nature. It must be remembered, too, that 

 there were serious difficulties in the way of arriving at a 

 definite decision on many points at a time when the new 

 systematic views had not as yet been thoroughly discussed 

 nor their full significance appreciated. It seems to me, I 

 confess, hardly just to make the hesitating step of those who 

 were entering an untried region, and were unable to compre- 

 hend fully at first all the new conditions with which they had 

 to deal, a matter of reproach. Their work has no doubt been 

 a progressive one and has resulted in a much fuller and more 

 thorough application of the new principle than they had 

 realized at first. And I am far from denying that there are 

 still oversights to be rectified and inconsistencies to be can- 

 celled. Dr. Jullien finds one of the chief grounds for the 

 charge of inconsistency which he brings against many of the 

 later writers on the Polyzoa in their retention of the genera 

 Retepora and Cellepora — artificial assemblages of species 

 which, according to the new views, have no claim to be 

 maintained. It is quite true that in my ' History ' I have 

 retained both these genera ; but it is also true that in the case 

 of Retepora I have pointed out the inadequacy of the fenes- 

 trate structure of the zoarium as the basis of a genus *, and, 

 remarking that the zooecial characters of the British species 

 are similar, have left the rest of the group to be dealt with 

 after a fuller study of foreign species than was then possible. 

 As to Cellepora, in retaining it I did so on the ground that 

 there were zooecial characters on which it might be founded. 

 This opinion I have long since abandoned ; but neither time 

 nor opportunity has been available so far for the exhaustive 

 examination of the numerous forms which have found a place 

 in the Celleporine group, on which alone a reconstruction 

 could be founded. The genera Retepora and Cellepora I 

 regard, and have long regarded, as merely provisional. 



* " The reticulation is merely a form of ramification, aud is probably 

 entitled to no more systematic weight, apart from the characters of the 

 zooecium, than the simple branching, which was the distinction of the old 

 genus Eschara. The retiform zoarium is associated with very different 

 types of cell, whilst, on the other hand, a form in my possession . . . which 

 cannot be distinguished generically, in other respects, from many of the 



Retepora, exhibits no trace whatever of reticulation Strongly 



marked as is the fades which its peculiar habit of growth gives to the 

 Retepore, we must not assign too much weight to it as a clue to natural 

 affinity." (Hist. Brit. Mar. Pol. i. p. 339.) 



