GRAPTOLITES OF NEW YORK, PART 2 473 



graptus as having the "gonosome provided with scopulate reproductive 

 processes." 



Freeh (1897, p.67 1 ] in pointing to Lapworth's figures of L. cos- 

 tat us and margaritatus holds that Lasiograptus is a retiolitid, the 

 fibrous bundles forming a part of the periderm of the rhabdosome instead 

 of free appendages, whereby the difference from Retiolites would consist in 

 the fact that the central part of the theca is developed stronger than the 

 apertural part. Lasiograptus is accordingly defined as follows : " Rhabdo- 

 some similar as in Retiolites, but the central part of the thecae stronger 

 developed ; the fibrous tissues reduced between the latter and the periphery." 



The " reproductive sacs " of G r a p t . whitfieldi and L a s i o g r . 

 bimucronatus are by the same author in another part [p. 5 5 1] of the 

 above cited work — on account of the finding of gonangia in Diplograptus 

 by the present writer — suggested to have had a protective function 

 (" Deckschuppen ") or to have served as nectophores instead of having been 

 generative organs. 



In regard to the American specimens bearing these appendages and 

 identified by Hall with G . whitfieldi, Lapworth has stated [1877, p. 1 34] 

 that they are clearly distinct from that species and most probably belong to 

 a form of Lasiograptus, resembling L. bimucronatus, Nicholson and 

 in the Proceedings and Transactions of the Royal Society of Canada [1886, 

 p. 1 78 ff] has cited L . mucronatus and bimucronatus as synonyms. 



It becomes evident from this brief history of the genus, that neither its 

 characters are well known, nor its taxonomic position clearly established, 

 and that the species are not clearly differentiated. I have for these reasons 

 and because of the well known difficulty of reading the structure of rhab- 

 dosomes from shale material, brought together as much material as possible 

 of this puzzling group of forms and compared this material with Hall's 

 types. The Normanskill shales at Glenmont near Albany and those of 

 Mt Moreno proved especially rich in remains of Lasiograptus with append- 

 ages. The latter, as well as the whole rhabdosomes, exhibit in these collec- 

 tions an astonishing diversity of appearances and modes of preservation, 



