454 ANNUAL REPORT SMITHSONIAN INSTITUTION, 19 3 8 



that Baiera was a companion of Ginkgo in Jurassic and Triassic forests 

 and had a wide geographical range. Its reproductive organs, so far 

 as we know, conformed in essentials to the Ginkgo plan. 



Another genus is Ginkgodium, characterized by leaves similar 

 in venation to those of Ginkgo but narrower and rather different 

 in shape: leaves of this generic type are comparatively rare; they 

 were first described from Jurassic rocks in Japan nearly 50 years 

 ago, and, later, recorded from Jurassic rocks in southern Russia. 

 Nothing is known of the structure of Ginkgodium, and for that reason 

 the genus is of secondary importance. In 1913 Dr. Hamshaw Thomas 

 discovered a new type of fossil in a Jurassic plant bed in western 

 Yorkshire, to which he gave the generic name Eretmophyllum. The 

 leaves, 4 or 5 inches in length, are in shape like a rather narrow- 

 bladed paddle, hence the name, from the Greek word eretmon=oar or 

 paddle. The lamina has several parallel veins and resin sacs; the 

 structure of the superficial layer is consistent with close affinity to 

 Ginkgo. Other examples of the genus are recorded from Jurassic 

 rocks in southern Russia, Afghanistan, and Sardinia. Despite the 

 lack of reproductive organs it is generally believed that the leaves 

 known as Ginkgodium and Eretmophyllum may be safely included in 

 the Ginkgo group. 



We now come to some genera which differ more widely in form 

 from those of the living maidenhair tree but are confidently accepted 

 as allies that have long been extinct. The name Phoenicopsis (from 

 the Greek Phoinikeios— of the date or palm tree) is applied to leaves 

 comparable in shape to pieces of ribbon a few inches long and varying 

 from half an inch to rather more or less in breadth; the veins are 

 approximately parallel and occasionally forked. A characteristic 

 feature of this and certain other genera is the occurrence of leaves 

 in a crowded bunch on a very short shoot which is clasped and hidden 

 by tiny overlapping scales: the scales protected the shoot when it was 

 a bud and as the bud expanded they persisted at the base of the leaf 

 cluster. Phoenicopsis leaves have been described under several 

 specific names and from many parts of the world: Siberia, Afghanistan, 

 Turkestan, China, Japan, Spitsbergen, southern Sweden, Greenland, 

 numerous European localities, including Great Britain, and else- 

 where. The genus was very widely spread in Jurassic floras and it 

 was also a member of Rhetic and early Cretaceous floras; it probably 

 existed as far back in the geological time scale as the Permian period. 

 It has been possible to investigate the epidermal structure of several 

 species of Phoenicopsis and the facts thus obtained confirm the opinion 

 of Oswald Heer, who in 1876 was the first paleobotanist to describe 

 this old type of Ginkgoalean foliage. The very short branches, each 

 bearing a tuft of six or more grasslike leaves, may be compared on a 



