THE GRAPTOLITES. 



THERE is, perhaps, no better illustration in geology of 

 the value of detailed work than that which is fur- 

 nished by the group of organisms, to the consideration of 

 which this article is devoted. Formerly viewed with sus- 

 picion by biologist and geologist alike, and frequently 

 altogether ignored, we find the graptolites now treated 

 with respect even by those who have not devoted special 

 attention to them. Their value is generally recognised as 

 aids in the determination of the age of strata, but besides 

 this, a detailed study of the group will undoubtedly throw 

 light upon the physical and climatic conditions under which 

 the strata containing graptolite remains were deposited, and 

 also upon the evolution of the various forms of graptolites. 

 Every one will admit that the appreciation in which grapto- 

 lites are now held is largely due to three papers by Professor 

 Lapworth, one of which treats of these organisms from a 

 biological (i), and the second (2) and third (3) from a 

 stratigraphical point of view ; and the publication of these 

 papers is doubtless largely responsible for the appearance 

 of a large number of memoirs devoted to a study of the 

 group under consideration which have been written of 

 recent years. These recent memoirs it is the object of 

 this paper to consider. 



The memoirs, early and more recent, treating of the 

 graptolites are scattered through a variety of publications, 

 but an excellent bibliography compiled by Otto Herrmann 

 and published in his Inaugural Dissertation (4) gives a list 

 of these memoirs up to and including the year 1883. Even 

 with this guide the student has much difficulty in obtaining 

 access to some of the publications, and a general monograph 

 of the graptolites has yet to be written. In the list of 

 " Monographs which are promised or are in course of 

 publication " appended to the last " Monograph of the 

 Palaeontographical Society" we note "The Graptolites," by 

 Professor Lapworth, and all geologists must hope that ere 



