Revieivs — Wachsmuth Sf Springer's Monograph on Crinoids. 279 



is by no means the prerogative of writers on crinoids. Many- 

 descriptions issued forty years ago as "preliminary " remain uncom- 

 pleted to this day. It is pleasant to find that the earlier English 

 authors are not accused of similar bad faith ; at the same time, "their 

 descriptions in many cases are so primitive that neither genera 

 nor species can be identified." 



The account of the American localities for fossil crinoids, given in 

 this part of the work, is interesting and useful enough to indicate 

 the value there would be in a complete list of such localities with the 

 geological horizon as now ascertained. If the names of the chief 

 collectors could be added, as here, and also a list of the chief species 

 from each locality, so much the better. There are in the Old World, 

 and doubtless in the New, numerous ancient collections of North 

 American crinoids, with somewhat imperfect labels bearing names, 

 both of locality and horizon, which it is hard to identify with names on 

 modern maps or in modern manuals of geology. Nor would it be 

 only on such obscurities that the table we desire would throw light. 

 If drawn up by a competent authority, such as Mr. Springer, it would 

 advance the study of distribution in space and time, an accurate 

 knowledge of which is so necessary to the zoological evolutionist. 

 In this research no help is to be despised. As our authors say 

 in a passage that comes with great weight from practical collectors 

 and palaeontologists : 



" The trouble is that all our generalizations are necessaril^r based 

 upon the Crinoids as they are represented in our museums, and not 

 upon the Crinoids as they actually existed in geological time, which, 

 is a very different thing. It is like trying to reconstruct a book 

 from detached fragments of the chapters, some of them written in 

 hieroglyphics for whose decipherment the key has not yet been 

 found. We are accustomed to speak of the imperfection of the 

 geological recoi-d, but it is doubtful if in our practical studies we 



always bear in mind what this really means How much 



do we actually know of the life represented in the rocks accessible to 

 us ? Nearly all the known Silurian Crinoids come from the out- 

 croppings of the strata at two localities in Eui'ope, and three or four 

 in America. The Devonian exposures producing well preserved 

 specimens are ev%n more limited. The Lower Carboniferous 

 collections are better and more widely distributed, but are in- 

 significant after all. Take the Burlington and Keokuk limestones, 

 which in a few localities have produced more Crinoids in number and 

 species than any other formation. They consist of several hundred 

 feet of strata almost entirely composed of the comminuted remains of 

 countless myriads of Crinoids — fragments which are worthless to the 

 Palgeontologist. It is only rarely that a thin layer is found in which 

 the calcareous skeletons are preserved well enough for study; — little 

 basins of limited extent, in which, during a period of temporarily 

 quiet waters, the Crinoids lived, died, and were imbedded at sufficient 

 depths to escape the destructive effects of shore action. If the 

 collector happens to be present when one of these colonies is un- 

 covered by the quarrymen, the specimens may be rescued for the 



