232 Geohijical Society. 



cntiivly to the Lowvr Heaclon Beds, and consist of fresliwater 

 and hnickish-wator (more or less calcareous) dej^osits, laid down 

 apparently in wide shallow lakes and lacfoons. Svu-h habitats are 

 the most favourable to the growth of Ciiaraeeie, and several of the 

 beds have yielded numerous remains of these ))lants. 



Theiv is a great diversity in the fruits of Chnra found, repre- 

 senting evidently a numl)er of species, belonging to several different 

 sections or genera. \\\\\\ the exception of a few, which are ])ossibly 

 abnormal variations, tlie fruits can be roughly grouped under the 

 following eight types : — 



I. Tuberculate series. (Type of C. tuherculata 'Lje\l = Ko8mogyra Stache, 

 emeinl.) 

 (a) Splicrical. 

 (6) Obovoid or pyriform, with (li.stinctly prolonged base. 



II. Non-tnberculate series, 



(r) Large spherical, diam. c. 1 mm. (type of C. medicaginnla Brongn.). 



(<?) Large ellipsoidal (type of C. helirteres Brongn.). 



(e) Medium-sized, subglobose, tapering more or less at both ends, 



if) Cylindric-ellipsoidal, showing more numerous striae. 



{(j) More or less pyriform : that is, definitely tapering towards the 



base. 

 {h) Minute, snbglobose-ovoid (long. = c. 350 to 500 /i). 



It is difficult to determine the exact number of species found, 

 on account of the extreme variability of some of the forms, but 

 the Authors consider that at least twelve ma}^ for the present, be 

 conveniently treated as distinct. 



The vegetative remains are comparatively few, consisting of 

 minute portions of stems and bi-anchlets of different diameters, 

 and these it is impossible at present to connect with any particular 

 ty])es of fruit. 



Though investigations of some earlier formations have shown 

 that there are extinct forms of Chanice;e exliibitin^ important 

 points of difference from their living representatives, the remark- 

 ably distinct and characteristic oogonium of five elongated spirally- 

 twisted cells has remained constant certainly as far back as the 

 Inferior Oolite, and it is onl}'^ in earlier formations that any doubt 

 arises as to whethi-r bodies are or are not Chora fruits. 



Characeie are found in still fresh or brackish water all over the 

 world, under widely different conditions as regards heat, etc., and 

 may therefore be exjwcted to occur in almost all freshwater 

 formations. For these reasons it is suggested that the fruits of this 

 group of plants, when more widely collected, may prove of consider- 

 able value as zonal fossils for the correlation of lacustrine deposits 

 lying in isolated basins. Doubtless, on account of theii* small size, 

 tlie Characeifi have in the past often been overlooked. 



