THALLOPHYTES, BRYINAE. 37 



the Middle Oolites (Oxford beds) of France. It is only in rare cases that 

 the thallus of the Charas is so preserved as to show its form ; it is usually 

 broken up into small tubular fragments. The more perfect state occurs 

 only in the most recent fresh-water deposits, for instance in the tuffs of 

 Cannstadt and Weimar, in which our common species Chara hispida is 

 found incrusted, as if by a recent calcareous spring. In the case of all 

 older forms we have nothing but the remains of the oospores with their 

 rind, and in these the calcareous shell only has been preserved ; the crown 

 is always wanting. The fossil specimens show an orifice which answers 

 to the point of attachment ; the pedicel-cell not having been calcified 

 has disappeared. 



It has recently been shown by Munier Chalmas 1 that an entire group 

 of fossil organisms hitherto placed among Foraminiferae is connected -with 

 the family of Dasycladeae, and especially with those members of it in which 

 the membranes are calcified, namely the genera Cymopolia and Neomeris. 

 Unfortunately there are several serious difficulties in the way of an exact 

 and full description of this group. The recent species belonging to it are 

 still little known, I have had a monograph on the subject for some time in 

 preparation, and Munier Chalmas has not yet published his elaborate 

 investigations into the fossil forms ; in his preliminary communication he has 

 given the names of many genera, but no descriptions of any of them. There 

 is also some uncertainty about the nomenclature ; Munier Chalmas' genus 

 Polytrypa is Giimbel's 2 Dactylopora, and his Dactylopora is named by 

 Giimbel Thyrsoporella. I satisfied myself on this point when Munier 

 Chalmas was kind enough to'explain a number of his genera to me. 



The unicellular thallus of the recent genus Cymopolia (Fig. 2) has an 

 exceedingly complicated structure. It forms a tuft of branches which branch 

 by repeated dichotomies, and each branch is composed of a row of cylindrical 

 calcified members united together by short flexible connecting pieces which 

 contain no lime. The surface of the members is marked out into tolerably 

 regular areas in the manner of a honeycomb. At the extremity of every 

 branch is a pencil of copiously branched hairs, which envelopes and conceals 

 the youngest members as they are forming on the branch. The dichoto- 

 mous branching takes place only in the connecting pieces which are not 

 calcified. Each branch of the thallus consists of a central tube or filament, 

 which is rounded at the extremity and beset at regular intervals with many- 

 membered whorls of lateral branches ; its lumen also is uninterrupted, and 

 it shows only a slight stricture at the joints between the calcified members. 

 The membrane of this central tube is of great thickness and stratified, and 

 has no deposit of lime in any part of its substance. The lateral branches 



1 Munier Chalmas (1). 2 Giimbel (1). 



