222 NATURAL SCIENCE. October. 



rather regrettable that these Devonian Brachiopods should have been 

 sent to another collection. We have also noticed in the Monograph 

 on Devonian Fossils above alluded to very numerous acknowledg- 

 ments of the " great kindness " and " very kind help " received by 

 the author from most of the assistants in the Geological Department 

 in the British Museum. Doubtless the gentlemen in question are 

 only too deHghted to aid so enthusiastic a worker, but the public and 

 the Trustees may well ask where the gain is to their Museum. 



Graptolites. 



Cambridge geologists, following the lead of Mr. J. E. Marr, are 

 paying much attention to graptolites, and it gives us pleasure to 

 present them and our other readers with the article on the structure 

 of those animals contained in this and the previous number. The 

 views of Gerhard Holm have been fully placed before English 

 palaeontologists by the translations of his papers that have appeared 

 in the Geological Magazine, whereas the slightly different opinions 

 and important results of Wiman, with the exception of quite a short 

 review in the Geological Magazine for September, 1895, have not 

 received any exposition in the English language. The observations 

 of this Scandinavian author, as well as of those quoted in Dr. 

 Wiman's paper, refer to the morphology of the graptolites ; but our 

 readers are not likely to forget that these animals are of even greater 

 importance in their geological aspect, and of the recent results in this 

 direction a concise account was given in Science Pyogvess for July of 

 this year by Mr. Marr, whose own applications of these fossils to the 

 correlation of strata have not been among the least important. 



For the correlation of strata it is naturally most necessary that 

 the determination of the species should be exact. " More harm," says 

 Mr. Marr, " is done by a wrong determination than good by a correct 

 one. The graptolites are by no means easy of identification by those 

 who have not made them a special study, and it is particularly 

 desirable that no determination should be recorded by tyros, unless it 

 is absolutely certain, for when once a wrong name has crept into a 

 list it is exceedingly difficult to remove it." These remarks are quite 

 as applicable to other fossils as to graptolites, and may well be com- 

 mended to the notice of the hard-working gentlemen who draw up 

 the ponderous lists of fossils published in the Memoirs of the Geological 

 Survey. It is now generally supposed that the deposits in which 

 graptolites are found were deposited in deep waters at some distance 

 from continents, since graptolites are often found in association with 

 animals of a deep-sea habit, and especially with tests of Radiolaria. 

 This, however, as Mr. Marr appears, though not very clearly, to 

 suggest, is not due to the absence of graptolites from rocks of very 

 different character deposited close to land, such as the coral-reef rocks 

 of Gotland, but merely to the fact that deposition was so slow in 



