ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 1021 



species of Azolla, three are included in the subgenus Euazolla : — 

 macrospores crowned with three float-corpuscles ; rnassulaa of the 

 microspores armed all round with rigid glochidiate processes ; root- 

 fibres solitary ; and two in the subgenus Rhizosperrna : — Macrospores 

 crowned with numerous float-corpuscles ; roassuke of the microspores 

 armed on one side with a few weak prickles without glochidiate tips ; 

 root-fibres fascicled. The genus Marsilea includes forty species dis- 

 tributed into a number of groups, distinguished by the form and 

 structure of the pedicel. Or these forty species two are new. 



Fructification of Sigillaria.* — Dr. C. E. "Weiss contests the 

 conclusion of Renault f that the Sigillaria? may be divided into two 

 groups, one belonging to Gymnosperms, the other to Vascular Crypto- 

 gams. He considers them to be exclusively of the latter character, 

 the cones relied on by Renault as showing an affinity to Gymnosperms 

 not really belonging to Sigillaria at all. 



Muscineae. 



Development and Dehiscence of the Sporogonium of Hepa- 

 ticse.t — M. Leclerc du Sablon has examined this subject in great 

 detail, taking as a type in the first place Frullania dilatata. In the 

 very young sporogonium sixty-four cells are differentiated at the 

 summit ; the centre ones are a little more elongated vertically than 

 the rest, and form a kind of cap beneath the epidermal layer. These 

 cells have denser protoplasm and a larger nucleus than the other cells 

 of the sporogonium; and it is from them only that the spores and 

 elaters are developed. Each of them subsequently divides into four 

 by two vertical walls parallel to those already formed ; the cap is there- 

 fore now composed of 256 cells. These cells now elongate in the 

 direction of the axis of the sporogonium, and then become differ- 

 entiated into two kinds: — in the one the nucleus undergoes repeated 

 divisions, and these give rise to the mother-cells of the spores ; in 

 the other the nucleus does not divide, and the protoplasm forms spiral 

 granulations which become the elaters. These two kinds of cell are 

 equal in number, each alternating regularly with the other. 



Variations from this type are described in the cases of Scapania 

 compacta, Pellia epiphylla, Aneura pinguis, Targionia hypophylla, 

 Bebonlia hemisphserica, and Spliserocarpus terrestris. 



Witli regard to the structure of the sporogonium, Hepatic® may 

 be divided into two groups : — 1, the Jungermannieae, where the walls 

 are composed of two layers of cells furnished with ornaments, and 

 opening by four valves; and 2, the Marchantieae, Targionese, and 

 Riccieaa, in which the wall consists of a single layer of cells without 

 ornaments or nearly so, and bursting irregularly at maturity. 



* SB. Gesell. Naturf. Freunde Berlin, 1SS6, pp. 5-12 (3 figs.). See But 

 Centralbl., xxvii. (1S86) p. 58. 



f See this Journal, ante, p. 288. 



t Ann. Sci. Nat. (Bot.), ii. (1SS5) pp. 126-80 (5 pis.). Cf. this Journal, v 

 (18S5) pp. 91, 276, 832, 840, ante, p. 479. 



