I- X X 1NTRODU CTION . 



(his nomenclature is uncouth and bewildering) ; but his 

 knowledge of Polyzoau form is perhaps unsurpassed, and 

 by his clear diagnosis and splendid plates he has given us 

 a new revelation of the structural variety and beauty 

 of the class. 



We owe to Prof. Smitt * the first serious attempt to 

 substitute a natural system for the purely artificial ar- 

 rangements hitherto in use ; and it may at least be said 

 that, if he has not overcome all the difficulties incident to 

 the work and has left many problems unsolved, he has 

 given us the most fruitful suggestions, and may perhaps 

 have struck the track along which future advances must 

 be made. 



He has aimed at a genealogical classification, starting 

 with the proposition that the variations of species follow 

 the line of their development and may be in great measure 

 explained by it. The Polyzoa, he remarks, as compound 

 animals offer great facilities for the study of the laws and 

 causes of variation. The differentiation of the colony gives 

 us a series of variations, running from the early and simple 

 states to the fully developed form, which is the parallel of 

 the series of differences amongst species. Thus the British 

 species of Crisia represent the evolutional stages of one 

 and the same type, of which Smitt regards C. geniculata, 

 Milne-Edwards, as the first and simplest. The forms 

 of this genus he would arrange, according to the law 

 of their evolution, in a series, the members of which, 

 springing from a common origin, will hold each its evo- 

 lutional grade. 



* " Bryozoa marina in regionibus arct.icis et borcalibiiB vivcntia," CEfv. 

 Kongl.Vet.-Akad.F6rh. 1867; "Kritisk Fortcekning," ibid. 18tt4 and fol- 

 lowing year* ; ' Floridau Brjozoa.' 



