POLYZOA. 409 



Silurian rocks. Their presence in Cambrian seas is, I believe, not 

 a matter of certainty, although there is something very nearly 

 approaching to proof of their existence even as early as Cambrian 

 times. I have specimens from the Wenloch shales, a group of 

 Upper Silurian rocks. Polyzoa seem to have abounded in Silurian 

 seas. During the Carboniferous period it would seem that they 

 were equally plentiful, and to judge from the specimens b efore u 

 they appear to have developed not inconsiderably. 



The Foenestellidce, or " Lace Corals," seem to represent the 

 highest, or at least the most beautiful, type of the Polyzoa of the 

 Carboniferous period. There are several specimens of these 

 beautiful organisms in slide No. 2. If you compare Figs. 4 and 5^ 

 I think you will agree with me that these little builders had 

 improved very much in their architectural designs since the close 

 of the Silurian period. Whilst those characteristic dwellers in 

 Palaeozoic seas, the Trilobites, were fast dying out, their little 

 neighbours, the Polyzoa, were not only holding their own in the 

 struggle for existence, but were developing into forms of greater 

 beauty. 



It has been observed by an eminent living naturalist that " in 

 the confederation of animated nature some races can boast of an 

 immemorial antiquity, whilst others are comparative parvenues." 



The Polyzoa belong to an ancient race. Some members of 

 this long-lived family have been contemporaries with the Trilobites 

 of Silurian seas, with Pterichthys and other extinct fishes of Devon- 

 ian times, with the Labyrinthodon and other great reptiles of the 

 Triassic period, with Ichthyosauri, Plesiosauri, and other gigantic 

 saurians of the Jurassic period (specimens of some of which adorn 

 the walls of the Lecture Hall of the Bath Literary and Scientific 

 Institution;, as well as with other remarkable types of more recent 

 periods, now also extinct. 



It must, however, be assumed that this interesting family of 

 Polyzoa has, like most other famiUes, experienced changes. One 

 branch — the lovely Foenestellidce — does not appear to have sur- 

 vived the Carboniferous period. We find, however, the family 

 represented by other branches in each succeeding geological 

 period, and we know that it is still well represented in the oceans 

 and seas of the present time by myriads of descendants (Fig. 6). 



