ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 659 



Lithoderma and Hildenbrandtia.* — Herr R. Wollny has found 

 Lithoderma fluviatile for the first time in Germany, aud describes the 

 structure of the unilocular sporangia ; he also gives a fuller descrip- 

 tion of the marine L. maculiforme. 



The frond of Hildenbrandtia rivularis he finds to be composed, not 

 of a uniform mass of cells, as usually described, but of closely packed 

 filaments quite distinct for their entire length. 



Laminariacese of Japan.f — Herren F. R. Kjellman and J. V. 

 Petersen describe several new species of Laminaria, Ecklonia, and 

 Alaria brought from Japan by the Vega expedition, of which L. 

 angustata represents the highest type yet discovered, with strongly 

 localized sori ; also the new genus TJlopteryx — of which the only 

 species has been hitherto known as Alaria pinnatifida Harv. — with the 

 following diagnosis : — Radix fibrosa ; stipes alatus, alis demum latis- 

 simis, undulato-plicatis, soriferis ; lamina cryptostomatibus prsedita, 

 costata, pinnatim ramosa ; soris in alis stipitis dilatatis expansis, 

 zoosporangia elongato-ellipsoidea vel subclavajformia inter parane- 

 mata lineari-clavaformia unicellularia dense stipata fovens. 



Vaucheria sessilis. J — M. E. Dewildeman describes a singular 

 form of this species, parasitic on leaves in a spring, in which some of 

 the filaments branch copiously at the extremity, the thick branches 

 interweaving into a kind of ball. These filaments were always barren. 



Auxospores of Cocconema and Navicula.§ — M. P. Petit describes 

 the mode of formation of the auxospores of Cocconema Cistula and 

 Navicula crassinervia. He regards it as a process of simple asexual 

 reproduction, never accompanied by any fusion of two masses of 

 protoplasm. It is simply a case of regeneration of the frustules due 

 to protoplasmic activity. 



Hoops of Diatoms.j| — Dr. J. D. Cox supports the view that the 

 hoops of diatoms are formed all at once out of the living contents of 

 the frustule, and not by accretions upon the edge. The most notice- 

 able difference between the hoops of different species of diatoms is 

 that some are hyaline, while others are elaborately figured and orna- 

 mented with markings more or less resembling those of the valves. 

 These latter are persistent, forming a permanent portion of the struc- 

 ture of the diatom, of which Isthmia nervosa and Biddulphia pulchella 

 are familiar examples. The hyaline hoop seems usually to belong to 

 the free-swimming forms, and those closely parasitic species in which 

 a single frustule alone remains sessile upon and closely adherent to a 

 larger alga or other support. A favourable illustration is afforded by 

 Aulacodiscus Kittoni. 



The normal form of this diatom is a convex disc with four short 



* Hedwigia, xxv. (1S86) pp. 1-5 (1 pi.). 



t Kjellman, F. R., and Petersen, J. V., Vegaexped. vetensk. iakttag., iv. 

 (18S5) (2 pis.). See Bot. Centralbl., xxv. (188G) p. 327. 



% Bull. Soc. Beige Micr., xii. (1886) pp. 66-8 (1 pi.). 



§ Bull. Soc. Bot. France, xxxii. (1885), Session Extraordinaire, pp. xlviii.-li. 

 (1 pi.). 



|| Proc. Amer. Soc. Micr., 8th Ann. Meeting, 1885. pp. 33-7 (2 figs.). 



2x2 



