part 3] CHAROPHYTA OF THE LOWER IIEADOX BEDS. 183 



The features essential to the satisfactory cleteiiniiiation of the 

 genera are, unfortunately, lacking in the fossil fruits. The types 

 numbered 11 & 12, however, so closely resemble the fruits of living 

 species of Toli/pella that we think there can be little doubt that 

 they are correctly placed under that genus. The rest have been 

 provisionally'' ]*etained \inder the parental generic name CJiara, 

 sufficient evidence not being available to place them under other 

 genera, although there is every probability that some do not belong 

 to the genus Chara in its restricted sense. It is probable tliat the 

 lirge globular and broadly-ellipsoid fossil fruits, with swollen tips 

 to the spiral cells suggesting a deciduous coronula, belong to a 

 genus akin to JVitellopsis. 



None of the fossil fruits that we have examined shows an}^ sign 

 of the lono-itudinal flattenino' characteristic of the o-enus Nitellu. 



The following t^^pes appear to us sufficiently distinct to justif}^ 

 their differentiation as species. Possibly some of those now re- 

 ferred to varieties may also prove to be distinct, especially when we 

 consider the similarity of the fruits of closely-allied living species. 



There are, in addition, a few fruits which we have not been able 

 to refer with certainty to any of the types described, but which 

 eitiier appear insufficiently distinct, or for which there is insufficient 

 material to justifj'- the assignment of a name to them (PL YI, 

 figs. 6-8). 



The presence of so great a number of more or less distinct types 

 in this series of beds is not surprising, in view of the number of 

 living species sometimes found growing together in the same piece 

 of water. In Hickling Broad (East Norfolk), for instance, Canon 

 Bullock-Webster has collected twelve species of Charophytes ; Avhile 

 M. Emile Gadeceau in his admirable monograph on the Lac de 

 Grrandlieu (near Nantes) records no less than seventeen species 

 from that lake. 



The measurements given here are those of well-developed 

 fruits, the smaller specimens often present being ignored. Many 

 imperfect fruits occur, and in such cases it is almost always the 

 apex which is wanting. The thickness of the spii'al cells is stated 

 when broken specimens in which the calcareous shell seems to have 

 attained its full development are available. 



1. Chara Wrightii, Salter in Forbes, Mem. Geol. Surv. 1856, 

 p. 160 & pi. vii, figs. 15-21. (PL lY, fig. 1.) 



Oogonium fere globosum, latitudine quam longitudine plerumque 

 majus, diaraetro c. 950-1100 /x ; cellulae spirales in statu maturitatis 

 convexse, latissimse (c. 150-200 /x) et crassissima? (c. 75-125 yi/), 

 leves vel nodulosse, in apice, supra collum constrictum, plusminusve 

 turgido, circ. septem convolutiones exhibentes ; foramen basilare 

 comparate parvum, cum conformatione variabili, plerumque paulo 

 dilatum, interdum cum ore lato. [Oospora fere globosa. diametro 

 c. 700-775^, liras humiles sex-septem exhibentes; cohors basilaris 

 diametro c. 150 /x.] 



