ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 225 



6. With the protection of the antheridia is associated also the presence 

 of paraphyllia in the axils of the antheridial bracts ; the presence of 

 paraphyllia is constant for a given species, and seems to be connected 

 with a sub-xerophilous adaptation (Gharidonanthus, Mastigophora did ados). 



7. The perigonial amphigastria are always well developed, and are very 

 similar to the sterile ; they are strongly developed throughout some 

 genera, somewhat reduced throughout others. 8. The number of an- 

 theridia in each perigonial bract is within certain limits constant in 

 each genus. In some genera the antheridia are always solitary, viz. 

 in Anthelia, Lepicolea, Chsetocolea, Lepidolsena ; in others they are either 

 one or two, viz. in Blepharostoma, Ptilidium ; and they are more than 

 two in Isotachis, Trichocolea, Chandonanthus, Mastigophora, Herberta. 



9. Amphigastrial antheridia are known to Schiffner in two genera 

 only, Herberta and Mastigophora, and though rare occur probably in 

 every species of those genera, thus affording a sound generic character. 



10. The amphigastrial antheridia are in every way similar to ordinary 

 antheridia. 11. The presence of amphigastrial antheridia is only 

 possible in such genera as have very large unreduced perigonial bracts ; 

 and besides that, also in the axil of each perigonial bract a larger number 

 of antheridia develop. They are therefore out of the question in all 

 plants with solitary antheridia. 12. The plants with amphigastrial 

 antheridia break through Leitgeb's rule, hitherto regarded as universal, 

 that only the dorsal segments form antheridia. 13. Herberta and other 

 genera show also clearly that not only the dorsally situated half of the 

 dorsal segment, but also, in certain circumstances, the ventrally situated 

 part has the power of forming antheridia — whereby also the second part 

 of Leitgeb's dictum loses its universal validity. 1-4. Sendtner -a filiform is 

 Schiff. is cleared up : it is Blepharostoma quadripartitum (Hook.) Stepb. 

 var. filiforme Schiff. ; B. quadripartitum of the Dusen collection is B. 

 pilosum Evans ; Lepicolea quadrilaciniota Sail, belongs to the genus 

 Blepharostoma. 



Structure of Riccia Bischoffii.* — 0. Juel gives an account of the 

 anatomical structure of Riccia Bischoffii Huben., collected near Upsala. 

 In the middle of its thallus it has the normal structure of a Eu-riccia, 

 that is, it has the usual vertical single rows or columns of assimilatory 

 cells, each four surrounding a narrow vertical air-canal ; the chloroplasts 

 of the assimilatory cells are arranged in those portions of the cells which 

 abut on the canals. In the wings of the thallus, however, the assimila- 

 tory tissue is peculiar in being modified ; the air-canals are stretched out 

 obliquely, and are each surrounded, not by four columns of cells, but by 

 a cylindrical group of six to fifteen cells (as seen in horizontal section), 

 and the surface appears reticulate. This wing-structure resembles that 

 of the Australian R. vesiculosa, and is of importance as forming a transi- 

 tion from the structure of Eu-riccia to that of Ricciella with its wide 

 air-chambers. 



Critical Forms of Aplozia.j — V. Schiffner publishes notes on some 

 critical forms of Aplozia of the very intricate group of the paroicous 



* Svensk. Botanisk Tidskrift., iv. (1910) pp. 160-6 (1 pi. and figs.). 

 -f Oesterr. Bot. Zeitschr., lx. (1910) pp. 451-5. 



