4d OUR COMMON BRITISH FOSSILS, 



classification may be for living forms, it is unphilo- 

 sophlcal to expect it will fit with equal accuracy those 

 of long bygone periods, when animals frequently 

 possessed characters which have since been divided 

 among different genera. Indeed, it would appear as 

 if the Graptolites were, in some respects, a class of 

 those "missing links" which connected two great 

 divisions of animal life now distinct from each other. 



The young geological student finds himself in no 

 small degree perplexed when he first endeavours to 

 find out the zoological relations of the Graptolites. 

 Page refers some of them to the true " sea-pens " 

 {Pennatnla and Virgiilarid)^ with which, however, 

 they have nothing in common, except the mere 

 external resemblance the double Graptolites bear 

 to them. The Pennatiilidcs are nearly related to 

 those familiar objects of our coasts, popularly called 

 "dead men's fingers" {Alcyonium digitatttm). Other 

 writers place the Graptolites among the Polyzoa, or 

 " sea-mats." They are now, however, regarded by 

 Lapworth, Hopkinson, and others as undoubtedly 

 Hydrozoa, and very nearly related to the " sea-firs " 

 {Sertularidce). They differ from the Sertularians in 

 some marked particulars, especially in the possession 

 of a solid axis — whence their general name of " Rod- 

 bearers " {Rhabdophord) ; among others. In the posses- 

 sion of characters which caused Professor Allman, 

 the great authority on the Hydrozoa, to regard them 

 as intermediate between the Hydrozoa and Rhizopoda 



