EQUISETACEiE. 83 



in these mummy-wrappings, which time will not permit me to 

 refer to more fully, observes : — " In none of these species, except 

 the vine, to which I have referred, which Dr. Schweinfurth has 

 discovered, and of which he has made a careful study, has he been 

 able to detect any peculiarities in the living plants which are absent 

 in those obtained from the tombs." I venture to think that it would 

 be difficult to produce better evidence of permanency of type. It 

 is not my intention to base any theory on the facts I have called 

 attention to. I leave that to those who possess a more extensive 

 knowledge or a more lively imagination than I can lay claim to. 



EXPLANATION OF PLATES IX., X., XL 



Plate IX. 



Eig. 1. — Transverse section throu'^h young stem of Epiisetum sylvatl- 

 cum, showing : — o., eiaidermis ; c, collencliyma, many of the 

 cells contaiiiing chlorophyll; s., vascular bundle sheath; 

 g, vascular bundle ; I, cortical air-cavity ; I', central air- 

 cavity ; r', air-cavity of the vascular bundles ; st., stomata. 



After Thome, x 1.50. 



>j 2. — A peltate scale, bearing the sporangia on its inner side facing 



the stem, five being visible (highly magnified), s..s. , spores, 



with the elaters unrolled ; c. , elaters. After Tliom^. 



Plate X. 



Fig. 1. — Prothallium of Eguisetum maximum, with eleven antheridia, 

 V, prothallium ; a. , antheridia. 

 -Prothallium (o), with archegonia («.), x 30. 

 -An antherozoid, x 500. After Thom^. 



-Portion of transverse section of stem of Hippuris vulgaris 

 (Mare's Tail) ; natural order, Haloragete. 



-Portion of transverse section of stem of Equlsetum arvenne, 

 showing : — u, central ; e, cortical air-cavities ; p, vascular 

 bundles ; ep. , epidermis ; s, air-cavities of vascular bundles, 

 X 50. 



Plate XL 

 Fig. 1. — Stem of Calamite, one-tifth natural size. After Figuier. 



,, 2. — Stem of Gulamites sucordii, Brong., as restored by Dr. Dawson. 



After Lyell. 

 ,, 3. — Radical termination of a Calamite from Nova Scotia. 



After LyelL 

 ,, 4. — Fragment of a stem of Eipiisetltea colnmnaris. 



,, 5. — I'ortion of the same, magnified. After Lyell. 



,, G. — EipusetiLmcolnmnare, natural size. After Hugh Miller. 



All drawn by W. G. Wheatcroft. 



