137 



ADDITIONS TO THE LIST OF TASMANIAN FOSSILS 



OF UPPER PALAEOZOIC AGE. 



By RoiJKJiT M. JonsHTOs, F.L.S. 



(Pj.ate.) 



The rnudstone bodH (Upper Pala^ozoie) in theneighbourliooci 

 of J fobart are extraordinarily rich in npirifers. Fourteen species 

 have already been noted in my recent work on the Geology of 

 Tasmania. A number of other interesting forms have been 

 collected by me during the last two or three years ; but 

 hitherto 1 have not had time to study them witli that care 

 which is desirable; for any one who has worked long in 

 our rocks must be aware of the many difficulties which are 

 presented when any attempt is made to determine the 

 characters of the Protean-winged spirifers of Tasmania. In 

 the rnudstone rocks casts alone are generally found ; and 

 although these are numerous and sharply mart-red, the casts 

 present such a wonderful range of variation when largo 

 numbers of the same species are subjected to examination that 

 the task of determining the central or most typical represen- 

 tative of each species, is extremely puzzling. If attention 

 were confined to a single specimen — as is often the case where 

 odd specimens are despatched to palaeontologists at a distance 

 — there would be less perplexity ; but it need hardly be stated 

 determinations so made, without the knowledge of local vari- 

 ability, must add greatly to the perplexities of the Held 

 worker who may have to determine whatever variety comes to 

 his hand by the aid of descriptions based upon odd types. 



All the winged spirifers of Tasmania are extremely variable, 

 and many species among these extreme forms are scarcely 

 separable from similarly variable allied species. /S'. convoluta, S, 

 lisculcata, H. vesper lilio, S. duodecimocosta, and <S'. avciula are 

 remarkable for the extreme variability in form and sculpture. 

 Added to the difficulties of the observant field worker are the 

 variety of modes in which they are presented in casts; some 

 showing sharp details of external surface of right valve; some 

 of left ; some of more or less blurred surfaces of one or both 

 sides of internal casts. The greater number, again, are 

 curiously distorted. It is not surprising, therefore, that many 

 able authorities have had frequently to revise the classifica- 

 tion of many of these forms, when other examples of an 

 abnormal form or type have been submitted to them. The 

 following six species, as determined by me from a series of 

 specimens of each kind, presented all the difficulties referred 



