10 CHABA. 



which usually supplies the evidence for the existence of these 

 plants in rocks of various ages, is too imperfect to enable us to 

 decide accurately whether the fragments should be referred to 

 Chara, Nitella, or other genera of Characece. 



In view of this difficulty it is better, therefore, to describe all 

 the Characeous "fruits" by the term Chara, if we regard the 

 generic name, when applied to fossils, rather in the sense of a 

 representative of a family than of the genus Chara as denned in 

 the more recent works on this anomalous group. 



We frequently find the statement that the oldest known fossil 

 Charas are those which have been found in beds of Muschelkalk 

 age from Moscow ; but in no case have I been able to discover a 

 reference to the author who first noted this occurrence. It is by 

 no means improbable that we must go much farther back in the 

 geologic series to find the earliest traces of Chara "fruits." In 

 a paper in the American Journal of Science for 1889, Knowlton 1 

 gives three figures of some "problematic organisms" which it is 

 difficult to believe can be anything but Chara oogonia. They are 

 described as minute spirally-grooved bodies 1*50 mm. 1*80 mm. 

 long, and 1'70 mm. broad, with a small aperture at one end; these 

 bodies occur in large numbers in Lower Devonian-Carboniferous 

 sandstones, and were mentioned in 1873 by Meek, 2 who spoke of 

 them as showing all the external characters of Chara. Knowlton 

 recognizes the strong likeness to this genus, but quotes various 

 opinions which throw a good deal of doubt on the plant-nature of 

 these small fossils. One objection is that the fossil bodies have on 

 their surface the marks of more than five cells, the number making 

 up the envelope of recent Chara oospores ; and in the living forms 

 these spirally-placed cells are twisted to the left, but in the fossils 

 to the right; this, however, Knowlton suggests is "no vital 

 objection to the supposition that this might have been an archaic 

 or original type from which the more modern forms have 

 developed." 3 



Other arguments against their Characeous affinities are (i) the 



1 I am indebted to Mr. Davies Sherborn for calling my attention to this paper 

 and to Ulrich's genus Moellerina mentioned below. Amer. Journ. ser. iii. vol. 

 xxxvii. p. 202. 



2 Report Geol. Surv. Ohio, vol. i. pt. ii. p. 219. 



3 Loc. cit. p. 204. 



