TRILOBITE HUNTING. 203 



ness to name fossils which has been displayed by 

 many geologists, some of whom were but poor natura- 

 lists. Now and then, from no better ambition, we fear, 

 than to perpetuate the name of the finder, and still 

 oftener from his ignorance of zoology, new genera 

 and species have been made, to the utter bewilder- 

 ment of those who now set out to study the 

 particular creature concerned. Differences of the 

 most insignificant kind, such as would hardly be 

 sufficient to constitute a variety, and some of which 

 were certainly not permanent, have been taken as 

 sufficient reason for the starting of a new species. 

 Owen has pointed out that the trifling differences 

 between Asaphus caudatus and Asaphus longi- 

 caudatus, chiefly in respect of the tail-spines, may 

 only mean that the one is male and the other 

 female. Then again, so much evidence has of late 

 been procured to show that trilobites, like other 

 Crustaceans, moult and go through various stages 

 of metamorphosis, that very likely a considerable 

 number of so-called genera and species are really 

 nothing more than different links in the life-chain 

 of the same individual. Who knows whether the 

 lowly, eyeless Agnostus may not after all be only, 

 as Owen hints, " the larval form of some large 

 trilobite " ? When we come to deal with the detailed 

 structure of the trilobite, we shall be confronted 

 with many other suggestions of this sort. Mean- 

 while we still have fifty genera and four hundred 

 species of trilobites, awaiting, we hope, some diminu- 

 tion, as fresh knowledge is obtained concerning 

 their embryology and life-history. 



