X PREFACE . 



gow, and himself made to that part of Ireland in the 

 summer of 1874. 



In concluding this brief preface, the Editor feels it 

 necessary to state that, while he most gladly gave Dr. 

 Bowerbank all the aid in his power during the pro- 

 gress of his work, and placed his collection unre- 

 servedly in his hands for description, he found himself 

 frequently obliged to dissent from the conclusions 

 arrived at by the author. In editing this posthumous 

 volume of his valued friend his aim has been simply 

 to leave it as Dr. Bowerbank's work. To have 

 attempted to indicate his own views would have been 

 to remodel the whole, and the species would have had 

 to be thrown into more numerous genera, defined on 

 different principles, while, on the other hand, the 

 number of so-called species would have been con- 

 siderably reduced. Great care will, however, require 

 to be used by the naturalist who shall hereafter attempt 

 to rearrange and redefine the species of British Sponges. 

 In every case the type specimen should be examined, 

 for to his certain knowledge subsequently found speci- 

 mens, during the latter years of Dr. Bowerbank's 

 life when his powers of observation were not so keen 

 as they had been, were frequently erroneously referred 

 to already named types with which they had no con- 

 nection. Let the reviser therefore be cautious and bear 

 in mind that hastily formed conclusions and lumping 

 of species which are really distinct is a greater fault 

 than for a time, if need be, keeping two forms apart 

 which are in reality referable to the same type. 



It may be useful to Spongologists to know that Dr. 



