378 SUMMARY OF CURRENT RESEARCHES RELATING TO 



On some Fossil and Recent Lithothamniese of the Panama 

 Canal Zone. — M. A. Howe {Bull. Smithsonian Inst. U. S. Nat. Mas., 

 1919, 103, 1-13, pis. 1-11). Detailed descriptions of, and critical 

 discussion on, three new species of fossil coralline algse from Oligocene 

 strata of the Panama Canal zone — Archseolithothamnium episporum, 

 Lithothamnium Vaughanii and L. isthmi. Lithoporella melobesioides 

 Foslie is also recorded from the same stratum in the Canal zone. 

 Hitherto only one species of fossil Lithothamniete has been recorded 

 from the Western Hemisphere — namely, Lithothamnium curasavicum K. 

 Martin, from the Island of Curagoa, In outward form and in its habit 

 of overgrowing old corals, A. episporum resembles A. erythrxum Foslie 

 f. durum from the Red Sea and East Indies, but differs in internal 

 structure and in its more superficial sporangia. In size and external 

 appearance Lithothamnium Vaughanii resembles coarse eroded conditions 

 of the living L. glaciaU Kjellman, but differs in structure. Both the 

 habit and structure of the three new species are well represented by 

 photographs. E. S, G. 



Historical Review of the Floridese. — A. H. Church (Journ. of 

 Botany, 1919, 57, 297-301). An historical account of the study of the 

 red seaweeds from about 300 B.C. — of the early attempts at record and 

 classification, and the striking advances that have followed successively 

 the work of Bornet and Thuret on sexual reproduction ; of Schmitz on 

 the development of the cystocarp and on the nature of cell-fusions, 

 together with his re-grouping of the families and genera ; of Oltmanns 

 on the true nature of the cell-fusions ; of Yamanouchi and others on 

 the life-cycle of Polysiphonia and other genera. A. G-. 



Additions to our Knowledge of Sargassum. — A. Grunow {Verh. 

 Zool. Bot. Ges. Wien, 1915, 65, 329-448 ; 1916, 66, 1-48, 136-85 ; 

 see also Bot. Centralbh, 1918, 137, 4-5). A posthumous work, in which 

 the author describes in detail numerous species and forms of Sargassum, 

 both new and old, and adds critical notes on synonomy and distribution. 

 The arrangement of J. G. Agardh is retained with but few exceptions. 

 /S. vidgare and S. subrepandum are very variable species, and many 

 others are difficult to determine. The paper includes 230 species, and 

 is invaluable as a handbook to the genus, since the author had access to 

 a large number of types. An index of species and synonyms completes 

 the work. E. S. G. 



Phaeophycean Zoid.— A. H. Church (Journ. of Bot, 1919, 57, 

 Suppl. ii., 7 pp.). A summary of our knowledge of the ciliated 

 reproductive cells of the brown alg£e — for example, the zoogonidia of 

 Ectocarpus, the gametes of Laminaria, the antherozoids of Fucus. The 

 minute structure of these cells is described, and their resemblance to 

 typical Flagellate. The asymmetrical habit, with the lateral insertion 

 of the two unequal flagella, is suggested to be of secondary origin. The 

 anterior flagellum is a tractor mechanism, while the posterior flagellum 

 is a trailer. The flagella are most efficient when measuring three to 

 four times the length of the body. Their primary function is to provide 

 a means of vertical ascent towards the light, and a speed of 1-2 ft. per 



