SILURIAN GRAPTOLITES. 



695 



North Pembroke. They there prove by their position, that the lines of slaty cleavage coincide 

 with the original laminae of deposit, along which these fossils are arranged, p. 461 *. 



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. 1. p. 56 to 8, f. 3. 

 " Priodon, Nilsson, Bronn, Lethsea Geognostica. 

 " Lomatoceras, Bronn, ib. p. 55. 



" Prionotus Nilsson, Hisinger Lethaea Suecica, p. 113, 114. 



" Very different opinions have been entertained as to the place which the Graptolites hold in the 

 series of living beings, but that of Professor Nilsson may come nearest to the truth, who conceives 

 the Graptolite to be a polyparium of the ceratophydian family. Yet I am more inclined to regard 

 them as belonging to the group Pennatulince, the Linnaean Virgularia being the nearest form in 

 the present state of nature to which they may be compared. 



" I am now acquainted with six or seven species of Graptolites, all occurring in the oldest fos- 

 siliferous strata, where they are associated with Trilobites, Orthoceratites, &c. Of the species above 

 alluded to, five belong to Scandinavia, and, of the other two, one is peculiar to Bohemian and the 

 other to French strata. The three specimens given me by Mr. Murchison belong to two species, 

 No. 1 and 2 being identical and agreeing with a Norwegian species which in my monograph I have 

 named Graptolithus virgulatus ; but as the memoir is still unpublished, Mr. Murchison may change 

 the name if he thinks it desirable. The species, No. 4., is new, and Mr. Murchison's name is 

 adopted," 



Generic characters of Graptolithus. 



Class Polypi. 



Order. Qj. Octactinia, Ehrenberg ? 



Family. Pennatulides ? 

 Genus. Graptolithus, Linn. 



" Polyparium indivisum, elongatum, sublineare, acuminatum, obtusiusculum, statu fossili 

 compressissimum, serratum. 



'" Polypi alternantes cum tubulo communi centrali communicantes, in fossili statu scepissime 

 secati, rarius bifarii, oblongi, acuminati. 

 • <c When the stem is cut off, the distinct bodies of the single polypes are seen alternating and 

 showing different forms when cut in different directions. 



" In the first edition of his Systema Naturae (1736), Linnaeus published a generic group under 

 the name Graptolithus. The first species he described several years afterwards in his travels in 

 Scania (p. 147.), where also a rude figure is given. This is the most common form of graptolites 

 in the Scandinavian transition formations, and as described and named first may be taken as the 

 typical form of the genus. When Linnaeus introduced specific names this species of graptolite was 



1 Graptolites have recently been found in rocks of the Silurian epoch in Ireland. Capt. Portlock, R.E., 

 has just published, in the first volume of the illustrations of the Ordnance Survey of Ireland, a figure of a beau- 

 tiful specimen, probably the same species as our G. Ludensis. 



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