128 ON PERMIAN ENTOMOSTRACA FROM 



risk than the fingers. Dr. Carpenter recommends the use of tlie 

 moistened tip of a camel's hair pencil in similar cases; and in in- 

 stances where the objects sought are extremely delicate, it will 

 be the more preferable instrument; but when the specimens, like 

 the Permian Entomostracciy possess a moderate degree of firm- 

 ness, they may be extracted with greater ease and celerity as 

 above indicated; and when an extensive series of examples is 

 required, expedition is of some value. With the assistance of a 

 common lens, and a pair of moderately good eyes, nothing more 

 is necessary. 



In my paper on the Permian Entomostraca, in the " Annals of 

 Natural History," (3rd series, vol. ii.), I proceeded, after some 

 prefatory remarks, from which the foregoing are slightly modi- 

 fied, to describe, first, the Cytlierklce, arranging the various forms 

 under twelve species; and next, the peculiar JBeyrichia-like 

 Entomostraca which Mr. Jones had formerly referred, first, to 

 Dithi/rocaris, and afterwards to Ceratiocaris : this I provisionally 

 termed a Leperditia, stating my belief that it would be found to 

 be characteristic of a new group, closely neighbouring on that of 

 Leperditia and Beyricliia. Having requested Mr. Jones to supply 

 me with his fully considered opinion on the value of these specific 

 and generic determinations (and proposing to incorporate his re- 

 marks with the reprint of my memoir), I have been asked by 

 him to place the description of the Beyrichia-like species first, in 

 this paper, as he has been able to get together and work out his 

 material, with respect to this species, much more satisfactorily as 

 yet, than in the case of the Bcdrdice and other Cytlieridce. He 

 tells me that the identification of the Permian Entomostraca is so 

 closely concerned with the correct determination of the Carboni- 

 ferous species that, until he has made every possible endeavour 

 to have a personal examination of all the Carboniferous forms 

 already described by palaeontologists, he cannot do justice to his 

 intended critical examination of the Permian Cytheridce. 



A valuable collection of the Carboniferous Entomostraca of 

 Ireland has been confided to his care by the kindness of Sir R. 

 Griffith; he has also the permission of Sir R. Murchison to use 

 the Irish and other specimens in the Geological Survey Museum ; 



