372 Review of the New York Geological Reports. 



structure were well suited to the habits of the family of ' sea 

 pens,' of which they form a genus. They were named Grapto- 

 lites by Linnaeus, and have since been partially described under 

 different names, by Wahlenberg, Schlotheim, Hisinger, Nilsson 

 and Bronn, The Danish naturalist Beck, who is preparing a 

 monograph of them, has supplied me with the following sketch. 

 From his remarks it appears that one of the species, very charac- 

 teristic of the upper Silurian rocks, occurs abundantly in Nor- 

 way and Sweden. Dr. Beck intended to name this species Grap- 

 tolithus virgulafus, but not yet having printed his monograph, 

 he authorizes me to use any other term, and therefore I adhere to 

 the name of G. Ludensis, which was adopted before I received 

 the description of the learned Dane. It does not however, ap- 

 pear certain that there is any real distinction between this fossil 

 of the Ludlow rocks, and the Prionotiis Sagittarius, Hisinger. 

 The fossil fig. 3, is not adverted to by Dr. Beck. It seems more 

 like Prionotus foliam, (Hisinger,) but differs from that species 

 in the number of foliations, and I therefore venture to suggest the 

 name G. foliaceus. This species was found in the calcareous 

 flags of Meadowtown, near Shelve, Salop, (Llandeilo flags.) 

 Fig. 4. of the same plate being unknown to Dr. Beck, he has, as 

 above stated, named it after me. The G. Murchisonii occurs in 

 the lower Silurian rocks and volcanic grits of the Llandrindod 

 Hills, Radnorshire." 



" These pen-like, serrated fossils have a great vertical range in 

 the older or ' protozoic' rocks, being found from the lower part of 

 the Ludlow formation, down to very ancient beds in the Cam- 

 brian System, in which they were collected for example, by Prof. 

 Sedgwick in Abereiddy Bay, North Pembroke. They there 

 prove that the lines of slaty cleavage coincide with the original 

 laminae of deposition, along which these fossils are arranged." 



Note on Graptolites ; by Dr. Beck. 



" Graptolithus, Linn., Iter. Scan. Wahlenberg, Hisinger, &c. 

 Esquisse d'un Tab. des Petr. de la Suede, p. 28. 



" Orthoceratites, Wahlenberg, Schlotheim, Nacht. Pet. I, p. 56 

 to 58, f 3. 



^^ Priodon, Nilsson, Bronn, Lethssa Geognostica. 



" Lornatoceras, Bronn, ib. p. 55. 



"Prionotus Nilsso?i, Hisinger, Lethasa Suecica, pp. 113, 114. 



