—43— 



In the absence of sufficient fruiting material I am unable to give any very 

 definite opinion on the question of the identity of C. leuconeurum and C. Whipple- 

 anum. Lesquereux and James give distinguishing characters in the fruit,* 

 apparently of some value, but so far as the vegetative characters are concerned 

 I have carefully compared various gatherings of C. Whippleanum, including a 

 small specimen of the cotype of C. Whippleanum kindly sent by Dr. Grout to 

 Mr. Dixon, and C. leuconeurum with the Portuguese plant and, though there is 

 a certain amount of variation in the width of the leaves, I can find nothing 

 whatever to justify the separation of the plants on these characters. 



The figure in the Natiirlichen Pflanzenfamilien, copied from Sullivant's 

 of C. leuconeurum, gives the leaf cells of this species as having normally two 

 papillae on each cell, but in the specimens which I have examined both of this, 

 of C. Whippleanum and of the Portuguese plant, I find most frequently one large 

 papilla situated about the middle of the lumen. No fruit has ever been found 

 on the Portuguese plant, which appears to be the male only. I have not been 

 able to find anything except antheridia on the material which I have examined 

 In this respect. 



The occurrence of Claopodium in Europe is interesting and it adds another 

 species to the rather small list of distinctively southern mosses which are com- 

 mon to the two continents. 



The substantial identity of the nearctic and palearctic moss floras has long 

 been recognized, and this identity is probably greater than our present nomen- 

 clature would seem to imply, as a study of the treatment of Pseudoleskea in the 

 two areas and a close comparison of the forms would, I think, show. The 

 probable distribution of this common flora by circumpolar land is also recog- 

 nized, but towards the south of both areas the species tend to become more 

 distinct. I do not, however, think that it is necessary to predicate Atlantis to 

 account for such as do occur in both. The distribution of many of these 

 was probably by way of circumpolar land also, though it may go back to a 

 more remote period. A large portion of such an early flora, the remains 

 of which are now found in the more southern parts of both regions, may 

 well have disappeared and the survivors are limited to such parts of the 

 two where approximately the same conditions obtain. There is no doubt a 

 good deal in common between the climate of the coastal regions of California 

 and that of Portugal. 



Dr. Best draws my attention to another example of discontinuous distribu- 

 tion in the genus in the case of C. pellucinerve (Mitt.) Best, which is found in 

 the Himalaya and again in the Yukon territory of Alaska. 



Other southern species common to Europe and N. America are Fabronia 

 pusilla Radd., F. octohlepharis (Schleich.) Schwgr., Haplohymenium triste (Ces.) 

 Kindb., Habrodon Notarisii Sch. and Trematodon longicollis Michx. The dis- 

 tribution of the latter in Europe is very remarkable, as it is limited to a very 

 few localities in Italy and the adjacent islands, where the ground is warmed 



* Dr. Best in his Revision of the Claopodiums (loc. cit.) reduces these alleged differences in. 

 the fruit to practically nothing. 



