18 GEOLOGICAL MEMOIRS. 



Genus 5. Retiolites, Barrande. 



Syn. — Gladiolites, Barrande. 



Characters. — Biserial ; the upper surface covered with a net- 

 work ; having a superficial central axis. 



Number of species, one. 



Note. — This genus differs in its characters so very much from the 

 rest, that it would be injudicious to name it afresh on the plan on 

 which the foregoing have been named, at the expense of the generic 

 appellation given by M. Barrande. 



Observations. — The generic name Dijmon having been laid aside, 

 Monoprion also, for the sake of uniformity, should be changed to 

 Monograpsus. 



It is not advisable that the name Graptolithus should be applied 

 to any group of the GraptoUthince ; for the Graptolithince collec- 

 ti^'ely will long be spoken of as '* Graptolites," as is the case with 

 " Trilobites," " Terebratulse," and "Ammonites." I have sepa- 

 rated Graptolithus gracilis, Hall, G. Hallianus, Prout, and Lopho- 

 ctenium comosum, Richter, from the family of the Graptolithince, and 

 placed them with the Sertularid(E. M. Barrande' s genus Bastrites 

 is so nearly connected with Monograpsus through the B. triangulatus, 

 Harkness, which was first a Bastrites and then a Monograpsus, that 

 I have placed them together. Birastrites also occur, answering to 

 Diplograpsus. 



In all Graptolithince the lower or basal extremity is the thinnest 

 end of the stem, in an upward or forward direction from which cells 

 or cell-germs are placed. 



The Graptolithince lived, like their existing allies, the Virgularice, 

 either free in the sea, or attached by a foot- stalk to the mud of the 

 shore ; some, perhaps, remained attached only for a short time. 



The surface of the Graptolites in the slate is frequently converted 

 into Talc, which has generally been taken for a silicate, and in some 

 Graptolite- schists traces of jet are present. 



[T. R. J.] 



On the Flora of the Transition Rocks. 

 By Prof. Dr. H. R. Goeppert. 



[Zeitschrift Deutsclu geol. Gesell. 1851, vol. iii. p. 185-207.] 



In announcing that he hoped soon to be enabled to publish the re- 

 sults of his researches in the Flora of the Transition Rocks, Dr. Goep- 

 pert observed that in the term *' Transition Formation " he hicludes 

 all the different strata older than the Coal Formation, — the newer 

 Grauwacke of Silesia and Saxony, which is evidently the analogue of 

 the Millstone Grit or Sandstone underlying the Coal-measures in 

 England, the Posidonomya-schist of the Harz and Nassau, the Car- 

 boniferous Limestone, the older Rhenish Grauwacke or Spirifer- 

 sandstone, and analogous rocks in North America, generally known 

 as Devonian rocks, and lastly the Silurian Formation. In all these 



