A comparison of Taeniopteris Carruthersi or various other “species” of Rhaetic fronds with the Jurassic species T. vittata illustrates the slight and unimportant differences on which specific separation is based. It is hopeless to attempt to draw a satisfactory distinction between the numerous Taeniopteris fronds from Upper Triassic and Jurassic rocks.
Taeniopteris vittata, Brongniart. Fig. 332.
The simple leaves to which Brongniart applied this name are characteristic of the Inferior Oolite flora of England, and examples of the same type are recorded from Jurassic rocks of India, Poland, the Arctic regions, Japan, China, Australia and other countries[1284].
Leaf linear-lanceolate, reaching a length of more than 20 cm. and a breadth of 3 cm. The lamina increases gradually in breadth from the base and tapers towards the apex. Numerous secondary veins are given off at right angles from a broad midrib: the lateral veins may be simple or forked close to their origin, near the margin, or in the intermediate portion, of the lamina.
It is exceedingly difficult to use Taeniopteris leaves of this form as evidence in regard to the Jurassic or Rhaetic age of plant-bearing strata. The species T. tenuinervis Brauns, as figured by Schenk[1285] from the Rhaetic rocks of Germany and Persia, and recorded from several other regions, presents a close agreement with T. vittata. Oleandridium lentriculiforme Etheridge[1286] from the Hawkesbury series of Australia is another similar leaf. The species T. vittata from the Yorkshire coast, represented in [fig. 332], shows a well-preserved petiole with a clean-cut base like that of the petioles of Oleandra neriiformis and other recent ferns which are detached from the rhizome by the action of an absciss-layer.
Fig. 332. Taeniopteris vittata. (British Museum No. 39217. ⅔ nat. size.)
A broader form of frond with similar venation was described by Lindley and Hutton[1287] as Taeniopteris major. An examination of the type-specimen from the Inferior Oolite of Yorkshire, now in the Manchester Museum, led me to doubt the necessity of specific separation from T. vittata[1288].
A smaller frond of the same general type as T. vittata is recorded from Wealden strata of North Germany and England under the name T. Beyrichii[1289].