ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 55 



those of the meristematic apex. The surface of the prothallus bears 

 numerous long rhizoids. The antheridia and archegonia are always 

 borne on the same prothallus without special localization. The male 

 gametes are coiled multiciliate bodies. The antheridia, developed from 

 superficial cells, stand out as spherical bodies, are very numerous, and 

 arise from all surfaces. The archegonium consists of an immersed 

 venter and of an emersed straight neck, consisting of four rows of cells 

 arranged in several tiers surrounding a neck canal. Like the antheridia 

 the archegonia arise from all surfaces. Both in their vegetative and 

 reproductive characters the gametophytes of Tmesipterls and Fsilotum 

 are remarkably similar. They differ in the following features : — 1. In 

 Tmesipterls the archegonia are more numerous than the antheridia, 

 Avhile in Fsilotum the reverse is the case. 2. In Tmesipterls the 

 archegonia appear in dense crowded groups, while in Psilotum they are 

 more separated or scattered. 3. The antheridia and archegonia of 

 Tmesipterls are twice as large as those of Psilotum. There is no struc- 

 tural resemblance between the gametophyte generation of the Psilotacese 

 and that of either Lycopodiwn or Equlsetum. The evidence shows 

 conclusively that Tmesipterls and Fsilotum are very closely related to 

 one another, but are very remote indeed in their phylogenetic relation- 

 ship, from both the Lycopodiales and Equisetales. There are no new 

 facts to upset the view that the Psilotaceaj are more nearly related to 

 the extinct Sphenophyllales than to any other known group of the 

 Pteridophyta. A. Gr. 



Notes on the Fern Genus Clathropteris. — Edward W. Berry 

 (Bull. Torrey Bot. Club, 1918, 45, 279-85, 2 figs.). Observations on 

 some new material from Virginia of the fossil fern Clathropteris platy- 

 phylla, with a discussion of its bearing on , the probable habit of the 

 genus. Fig. 1 represents the specimen itself, and fig. 2 a tentative 

 restoration of the frond of the species. A. Gr. 



Further Contribution to the knowledge of Platyzoma micro- 

 phyllum R.Br. — John McLean Tho:«pson {Trans. Roy. Soc. Edlii- 

 buryh, 1918, 52, 157-65, figs.). Additional facts relating to the mature 

 sporangia and spores of Flatyzoma, with a confirmation of the disposition 

 of the sporangia upon the pinnte, and of the well-marked differences in 

 sporangia! and spore-size and spore-output already recorded for this fern. 

 In the absence of knowledge of sporangial development and spore- 

 germination, it is unknown whether Flatyzoma be truly heterosporous. 

 Most of the sporangia are small, and the spore-output per sporangium in 

 these is approximately thirty-two. The remaining- sporangia are large, 

 and have an approximate output of sixteen per sporangium. The 

 sporangial stalk is typically three-rowed, but four-rowed stalks occur. 

 The annulus is usually irregular, but is interrupted by the stalk. The 

 small and large spores are the dominant types, and the spores of inter- 

 mediate size are developed when the spore-output in any sporangium is 

 greatly decreased. The three types of spore have similar spore- 

 markings. Their walls are thick, and no sign of germination is found 

 in any spore-type while still contained within the sporangium. The 



