12 Cephalozia. 



Q iiiTolucres and the ^f spikes consisted of broad leafy bilobed bracts, 

 and tliat the perianth and capsule were constructed exactly as in Ceplia^ 

 lozia. If tlie inflorescence and fructification, together with the mode 

 of branching, be considered to afford the essential marks for distinguish- 

 ing genera, then PteropsieUa can only rank as a subgenus of Cephalozia; 

 but for those who regard the difference between a frondose and a foliose 

 stem an adequate generic distinction, PteropsieUa will stand as a distinct 

 genus. 



The contrast in size and aspect is very great between Zoopsis and 

 PteropsieUa. In the former the stems resemble slender silken, or silver, 

 threads ; in the latter narrow green ribbons, and when much branched 

 are not unhke Ferns of the genus Pterojjsis. 



In Pkoto- Cephalozia the extreme of simplicity of structure is 

 reached, Xo stem, properly so called, exists ; there are consequently 

 no stem-leaves. From the base of the persistent and much-branched 

 prothallium springs a o flower, and certain branches of the prothallium 

 end each in a cf spike. The bracts of the inflorescence of both sexes are 

 exactly conformable to those of normal Cephalozia : the $ bracts bipart- 

 ite, tristichous and trijugous. The entire andr^cium is not half so long 

 as a single o bract, although it consists of 10 pairs of minute bifid mo- 

 nandrous bra?cts. The perianth is subulate, trigonous, and at the 

 mouth deeply cloven into 6 narrow capillaceo-acuminate valves, or 

 segments — very much as in PteropsieUa, notwithstanding the great 

 difference in the vegetative organs of the two groups. 



I found this curious little plant in two localities, not far from the 

 confluence of the Casiquiari and Eio Negro, in Venezuela, growing on 

 moist earth in shade and on little mounds thrown VL-p by mudworms. 

 I had akeady found a minute Phascoid moss {Ephemerum requinoctiale 

 Spruce) in similar sites ; it is the only Phascum known to me that grows 

 on the hot plains of the equator, and at first sight I took the Proto- 

 Cephalozia for a second species of the same genus ; for I saw on the lumps 

 of mould only a greenish confervoid film, with large x^erichgetia standing 

 out of it here and there — very like the Ephemerum serratum on our 

 garden-pots in England. The prothallium of all Cephalozim is narrow 

 ' and threadlike — very different from the suborbicular prothallium and 

 t propagula of Eadula, Lejeunea, and many other Hepaticffi : and it ap- 

 proaches the nearest of any among Hepaticfe to the protonema of true 



