cliv BRITISH GRAPTOLITES. 



forms of Graptolites hitherto collected from the " Upper Cambrian " (Tremadoc) 

 and " Lower Ordovicic " (Arenig) of New York State (the majority of which were 

 the fruits of the author's long-extended personal field researches), but embraces 

 also a detailed account and discussion of Graptolitic literature, knowledge, and 

 speculation up to the date of publication. 



The volume may be said to be divisible into two main sections : a first 

 (pp. 498 — 577), treating of the Graptolites in general, and a second (pp. 577 — 

 783), devoted to the description of the New York forms. 



The General Section opens with an outline Bibliography ranging from 1874 

 to 1903. This is followed by paragraphs dealing with the History of Research 

 among the Graptolites, in which the difficulties of the various branches of the 

 subject are pointed out, and the past stages of advance in knowledge and specula- 

 tion adduced and frankly discussed. In sub-section 3 the author, after passing 

 in review the methods of previous observers, describes the modes of illustration 

 adopted, which on the whole are similar to those followed in the present work. 



In sub-section 4, where Ruedemann is dealing with Terminology, he notes his 

 adoption of Tornquist's term " rhabdosome " instead of polypary as the equivalent 

 of the term " hydrosome " or the whole colony in the terminology of the " Hydro- 

 zoans," and suggests the new title " synrhabdosome " for each of those stellate 

 assemblages which have been interpreted by himself as colonies of colonies. He 

 calls attention to Lapworth's use (1897) of the term " graptotheca " as the 

 equivalent of " hydrotheca," but follows the general procedure in using the 

 simple term "theca" without qualification. He regards the Graptolites as 

 being separable into the two orders of the Dendroidea (Nich.) and the 

 Graptoloidea (Lapw.) and the latter as being divisible into the two sub-orders, 

 viz. Graptoloidea- Axonolipa (Freeh. Ruedemann, em.) and Graptoloidea-Axono- 

 phora (Freeh.). 



He draws a sharp distinction between the filiform tubular structure in the 

 Axonolipa, termed by Lapworth the " nema " or " nemacaulus," and the solid axis, 

 rod or " virgula " of the Axonophora, agreeing with those who hold that the latter 

 is wanting as such in the Axonolipa, but is apparently present inside the nema- 

 caulus in the polypary of the Diplograptida?, etc. He employs Hall's term 

 " funicle " for the common base of the component nemacauluses in the stellate 

 forms. 



After describing and illustrating the sicula and its relations, as worked out by 

 the Swedish authorities, he expresses his full accord with those who hold that 

 notwithstanding its resemblance to an ordinary serial theca it is always appropriate 

 to designate by the special title " sicula " alone. 



The various classifications of the Graptoloidea are passed in review, and that 

 of Lapworth (1879) accepted, with the additional families due to subsequent 

 discoveries. As respects the phylogeny of the Graptoloidea, the views of Marr 



