50 Dr. F. A. Bather — Eocystis. 



It was wlien I asked Dr. Matthew for the evidence on which he 

 recorded this Central European genus from the other side of the 

 Atlantic that he replied (in litt., February 5, 1900): "I may say 

 that the evidence is not direct. Socystites is founded on single star- 

 shaped plates. With these occur a few elongated plates somewhat 

 rectangular. The greater abundance of the star-like plates led me to 

 infer the probable presence of some such genus as Trochocystites^ as 

 the form to which the two kinds of plates belong." 



The name Trochocystites first appeared in print in 1859 (J. Barrande, 

 Bull. Soc. Geol. France, ser. ii, vol. xvi, p. 543), but then only as 

 a nomen nudum, and without a species. In 1860 De Verneuil & 

 Barrande (ser. cit., vol. xvii, p. 537) published a description, and 

 took as genotype the Bohemian species 2'. hohemicus Barrande, of 

 which no other description had till then been published. The fossil 

 from north of Sabero, Leon, Spain, which they figured (pi. viii, 

 iigs. 1, \a), was referred to that species " avec reserve"; it most 

 probably belongs to T. harrandei Mun.-Chalmas & Bergeron. 



If, then. Dr. Matthew's opinion is well founded there would follow 

 the unfortunate result that Trochocystis {-ties), as the name of a genus 

 with a clearly understood geuotype, would have to yield to Eocystis 

 (-ites), based on a species that depends in its turn on a single obscure 

 plate. It is therefore advisable to suhject Eocystites primavus to more 

 critical examination than it has yet received. 



There are, of course, more important reasons for undertaking such 

 an inquiry. Plates from the Cambrian rocks of widely separated 

 parts of the world have been referred to Eocystis, and the name has 

 also been doubtfully applied to a fairly well-preserved fossil cystid 

 retaining its brachioles — E. (?) longidactylus Walcott (1886). 



That I have been able to make this study is due to the kindness of 

 Dr. G. P. Matthew, who sent me forty specimens referred by him to 

 E. primcevus, and considered by him to afford the most complete 

 representation of that species. Eleven of these have, through the 

 generosity of Dr. Matthew, been retained for the British Museum, 

 and registered E 7602-7612. 



The specimens are labelled "Lower Cambrian, Division 1, C, 2, 

 Paradoxides-beds; St. John, N.B.", except three, said to come from 

 "RatclifE's Millstream". 



The matrix of all is a hard irregularly fissile shale, varying in 

 colour from dark grey to olive green, and weathering brown. The 

 substance of the fossils is either miich decayed or entirely dissolved 

 away, and the moulds or impressions are often stained with iron 

 oxide. The shale has been subjected to some lateral pressure, so 

 that in several cases the impressions are distorted. 



The impressions referred by Dr. Matthew to E. primcevus are 

 divisible into four groups; the numbers of the British Museum 

 representatives are quoted, as well as the letters which I attached to 

 Dr. Matthew's specimens. 



■ 1. Stellate plates, the typical Eocystites primcevus, E 7602-5, 

 E 7611-12; G. F. M. a, h, e,f. 



2. Plates with marginal pores. E 7608 ; G. F. M. c. 



3. Columnals. E 7605-7, E 7602 ; G. F. M. d, g. 



