ZOOLOaY AND BOTANY, MICROSCOPY, ETC. 225 



conifers, aud finds a very close correspondence between them. The 

 prolongation of the staminal shield which, in naost Cupressineae, pro- 

 tects the pollen-sacs when young, he regards, from analogy with ferns, 

 as an indusium. 



To the view previously expressed that the divisions in the embryo- 

 sac of phanerogams are nothing but divisions of the archespore, he 

 adds two illustrative examples, in Callitris quadrivalvis and Cupressus 

 sempervirens, in which the reduction in the divisions of the embryo- 

 sac does not go so far as usual. 



The author concludes with the following classification of vascular 

 cryptogams and phanerogams. 



I. Leptosporangiatae, 



A. Filices. 



(1) Homosporas (Polypodiacege, Gleicheniaceae, Cyathe- 



ace^j &c.). 



(2) Heterosporge (Salviniaceae). 



B. Marsiliaceae (Marsilia, Pilularia). 



II. Eusporangiatae. 



A. rilicales. 



(1) Marattiacese. 



(2) Ophioglossace^. 



B. Equisetineae. 



(1) Calamites. 



(2) Equisetaceae. 



C. Sphenophyllaceae (the formation of the sporangia re- 



sembles that of the heterosporous Lycopodinege, that 

 of the leaves corresponds to Equisetum). 



D. Lycopodinese. 



(1) Lycopodiacese. 



a. Homosporae (Lycopodium). 



h. Heterosporae (Lepidodendron, Sigillarieae ?). 



(2) Psilotaceae. 



(3) Selaginellaceae. 



(4) Isoeteae. 



E. Gymnospermge. 



F. Angiospermas. 



Lenticels of the Marattiacese.* — H. Potonie has examined the 

 structure of the lenticels in the leaf-stalk of Angiopteris crassipes, 

 evecta, Teysmanniana and Willinhii, and Marattia fraxinea ; and 

 describes those of A. evecta in detail. In all the Marattiacese the 

 stomata are arranged in rows, in the centre of which lenticels are very 

 commonly found. Their production begins by the walls of one or 

 more stomata, and of the epidermal cells which surround them, 

 becoming brown and dry ; the subjacent parenchyma then developing 

 into phellogen by repeated periclinal divisions, and the outermost of the 

 cell-layers also becoming brown and dry. The cell-walls cuticularize, 

 and small interstices appear between the dry cells ; the space occupied 



* JB. K. Bot. Gart. Berlin, i. (1881) pp. 307-10. See Bot. Centralbl., viii. 

 (1881) p. 70. 



Ser. 2.— Vol. II. Q 



