216 ON THE STUDY OF THE MOSSES. 



earth-mosses the capsule bursts irregularly, or rots away aud in its decay 

 liberates the spores. 



The lid or operculum varies in form, being "sometimes convex, as 

 in naany of the Bryums, or conical, (4 a, 12 «,) as in Physcomitrium 

 pyriforme, Tetraplm pellncida, &c., or it may be rostrate, (beaked,) (13 a,) 

 as in Dicranella heteromaUa, &c. 



Wlien the lid is removed, or has been cast off naturally, the 

 inner structure of the capsule may be seen, and in some mosses, such 

 as Pottia truncata, the mouth wiU be found to be naked, (4 e,) 

 but in many other cases it wiU be seen to be siUTounded by a 

 delicate fringe-hke appendage, called the peristome, (12 b, 21 b,) (Gr. 

 peri around, and stoma a mouth.) This fringe consists of minute tooth- 

 like processes, which are always some multiple of 4 in number, from 4 

 to 64, and the number is always constant in the species. This fringe 

 maybeeither single, (12 ?*,) or double, that is there may be an outer, (20 «,) 

 and an inner row, (20 b,) of these tooth-like processes. The teeth of flie 

 peristome vary in form and structure ; in some cases, as in certain of the 

 Weissias, they are very rudimentary ; in others, as in Funaria, they are 

 elaborately developed, and beautifully marked with transverse and 

 longitudinal striae or markings. The teeth are often simj)le, (12 b,) but 

 may be cloven, as in Dicranella heteromalla, sometimes straight, as in 

 Didymodoii rubellus, or much twisted, as in Tortula muralis, &c. In the 

 Polji;richums the mouth of the capsule is closed by a beautifully 

 reticulated diaphragm, to which the teeth of the peristome are 

 attached, (21 c.) This is pecuHar to the family of PolytrichacefB, so far 

 as British mosses are concerned. 



The study of the development of mosses is one of very gi-eat interest, 

 and worthy of the attention of all biological students. Space is too 

 limited to allow the matter to be dealt with here in anything like fulness, 

 and I must, therefore, refer those students who desire fuller information 

 to that grand work of Hofmeister (Eay Society's publications) on the 

 Germination, Development, and Fructification of the Higher Cr3T^)to- 

 gamia, pp. 129-181, where a most elaborate and exhaustive account will 

 be found. 



ON THE KELATION OF THE CEUST TO THE 

 INTEEIOR OF THE EAETH.- 



BY FKANCIS D. LONGE, F.G.S. 



The interior of the earth is bej'ond the reach of dii'ect observation, 

 but Nature brings within our hmited scope much evidence upon 

 which a general theory may be founded as to the relation between it and 

 the crust. That tho earth was once in a fluid state from heat is an 

 essential part of the theoiy of cosmogony established by Laplace, Newton, 

 HerschcU, and others. 



* Abstract of a Paper read April 18, 1878, before the Cheltenham Natiual Scienco 

 Booioty. 



