FLORIN: SYSTEMATICS OF THE GYMNOSPERMS 367 



ence to the genera Lehachia and Ernestiodendron, which he classified in a new 

 family, the Lebachiaceae. Both the vegetative and reproductive organs of these 

 genera were treated, and other less completely known types were also described, 

 including the upper paleozoic genus WalkomieUa (Florin, 1940a). Conifers of 

 triassic and Jurassic age were discovered, or became better known, by the efforts 

 of several investigators, who made use of the epidermal structures whenever pos- 

 sible. Of particular value is the extension in recent years by Harris (1942- 

 1952, 1943) and his students of our knowledge of the conifers in the British 

 Jurassic flora. Penny (1947) continued the work of Hollick and Jeffrey (1909) 

 on lignitic material of upper cretaceous conifers. He admitted that Brachy- 

 phyUum and Brachyoxylon may be related to the Araucariaceae, although the 

 contiguous type of tracheary pitting occurs with no greater frequency than in 

 several modern genera of the Taxodiaceae and Cupressaceae. Contrary to earlier 

 opinions, the internal structure of certain pine leaves was held to correspond 

 essentially to that of modern Haploxylon pines. Hollick and Jeffrey had con- 

 cluded that Geinitzia was of araucarian affinity, but Penny found no araucarian 

 features except the lack of resin parenchyma. The type of wood, the presence 

 of resin parenchyma, and the character of the ray cell, moreover argued against 

 the opinion that Widdringtonites could be araucarian. Frenelopsis was shown 

 to have the CupressinoxyJon type of wood, which confirmed the position of the 

 genus suggested by studies of the leaf epidermis (Carpentier, 1937; Romariz, 

 1946). It is closely related to, if not identical with, the genus Tetraclinis, to 

 which also certain isolated woods are believed to belong (Grambast, 1951). Flo- 

 rin (1940b) found in the coniferous floras of southern lands, including penin- 

 sular India, a total absence of now-living typically northern genera of Cupres- 

 saceae (cf. H.-L. Li, 1953), of Taxodiaceae (except Athrotaxis), of Pinaceae 

 and Cephalotaxaceae, of Taxaceae (except one Torreya-\ike form and presum- 

 ably also of Austrotaxus) , and of several extinct genera discovered in northern 

 lands. From the permian onwards, the southern conifer floras appear to be dis- 

 tinguished by pronounced features from contemporaneous northern floras. The 

 results contradicted the opinions of Studt (1926) that all conifers originated 

 in the northern temperate zone or in the arctic regions. Numerous special 

 studies of tertiary fossil conifers have been carried out, but a few examples of 

 recent developments will have to suffice here. Szafer (1949) investigated the 

 genus Tsuga in Europe, and indicated its probable evolution. Miki (1941) dis- 

 covered a new genus of the Taxodiaceae, 3Ietasequoia, which was subsequently 

 found not only to have been widely distributed in the northern hemisphere in 

 late cretaceous and tertiary times (Chaney, 1951), but also to be represented by 

 a living species native of China (IIu and Cheng, 1948; cf. Florin, 1952a). Re- 

 cent contributions to our knowledge of the history of the genus Sciadointys have 

 proved that this played an important role in the tertiary vegetation of central 

 Europe (Madler, 1939; Thiergart, 1949; Kirchheimer, 1950). A considerable 

 number of papers were also published on fossil woods, which (with the excep- 

 tion of AraucarioxyJon) were critically enumerated by Kriiusel (1949b) as a 

 complement to his earlier publication on the same subject. 



There has been much discussion of the taxonomic arrangement of certain 

 living generic groups of conifers. This applies to the Pinaceae (Flous, 1936a, b; 

 1938a, 1938b; Ferre, 1939, 1942, 1943; Ferre and Gaussen, 1945; Campo-Duplan, 



