﻿MOSSES FROM MiTTEN's HERBARIUM 99 



prorepens (Hook.) Schwaegr. The same is the case with M. sub- 

 mucronifoHum Hampe & C. Mull. I have examined the type of 

 this in Hampe's herbarium, and find no dilTerence of any kind. 

 The authors compare it with M. mucronifoHum (Hook. & Grev.) 

 Schwaegr., from Central and South America, and it is no doubt 

 nearly allied to that; but it would have been more to the point 

 if the authors had compared it with M. prorepens, which must 

 have been known to them. They do not, however, refer to it, 

 and neither in the description nor in the specimens of M. suh- 

 mucronifoHum do I find any character in the slightest degree at 

 variance with that species. 



It may be pointed out that there is nothing in the specimen of 

 M. prorepens to justify or explain the phrase in C. Mailer's 

 description (Syn. i: 725) of the basal cells as "minute quadratis" 

 they are narrowly linear as in all the allied species, and the phrase 

 is probably due to an error of writing or of typography. 



I have not been able to see a specimen of M. oocarpum C. 

 Miill., but judging from the description I should feel moderately 

 certain that it is only M. prorepens. The very short seta is the 

 only character suggesting a difference, and I shall refer to this 

 character as well as to the areolation in the group later on. 



It is necessary in order to explain the true relationships to make 

 some remarks on the character of the areolation. Brotherus 

 (Musci, Engler & Prantl, Nat. Pflanzenfam. i^: 484. 1903) 

 divides the species containing the group now being dealt with into 



Ka. Zellen der Lamina klein, etwa 0.025 mm. mit niedrigen 

 Papilien. 



Kb. Zellen der Lamina 0.05-0.07 mm., durchsichtig mit 

 hohen, zuweilen stacheligen Papilien. 



The broad distinction is a clear and well established one, but I 

 cannot follow him in the actual measurements. I have seen no 

 species— certainly there are none among the plants already men- 

 tioned — in which the cells approach the minuteness of 2.5 /t. 

 Careful measurements of a good many leaves of M, prorepens give 

 a fairly constant size to the upper cells, ranging from 7 to 11 /x I 

 while in the larger-celled species they are similarly constant, 

 ranging from 9 to 14 n. In neither case therefore do the measure- 



