513 
obtuse pinnata, pellucida, viridia, altera parte convexa (vid. ram. e.) 
altera (vid. ramos religuos) concava, qua parte capsulae ad pin- 
narum alas enascuntur parvae, oblongae, turgidae, exiguis aliquot 
ad basin squamis cinctae, tenui membrana constantes, quae luci ob- 
versae tres in singulo latere globulos ostentant, totidem foraminibus 
exilibus (duobus superius, reliquis per latera Iuscentibus) farinam 
fundentes ; semina non comparent.” , 
He further remarks that the plant revives when immersed in 
water, but in the dry state is contracted and convolute, not show- 
ing its structure ; that his figure was made too black in the course 
of the work [presumably by the engraver]; and that his speci- 
men was sent from Pennsylvania by Jo. Bartram, who had indi- 
cated that it grew in humid places. 
The principal figure given by Dillenius represents fairly well 
what we now know as Porella pinnata, though rather too stout 
and with leaves too closely set ; smaller accessory figures show 
the leaves in natural size and the “farinaceous capsules” ‘“ aucta 
magnitudine.’’ The latter are ellipsoidal or obovoid in form and 
exhibit a few perforations. 
The identity of the plant thus described and figured long re- 
mained a puzzle to botanical writers. In the Species Plantarum 
of Linnaeus it appears under the Musci between the genera Ly- 
copodium and Sphagnum. Linnaeus here bestows the specific 
name pinnata, quotes the ‘ Porella pinnis obtusis’ of Dillenius, re- 
fers to description and figure in the Historia Muscorum, gives the 
habitat as Pennsylvania, and states that he has never seen the 
plant and that Kalm has been unable to find it on its native soil. 
Mr. James Dickson was the first to detect that the Pored/a of Dil- 
lenius belonged to the Jungermaniaceae, and it may be worth © 
while to quote his narrative of the circumstances, especially as 
M. Le Jolis has somewhat recently* given the impression that the 
discovery was wholly a chance affair and also that Dickson con- _ 
sidered his Jungermannia Porella to be different from the Porella — 
of Dillenius. Mr. Dickson’s statements are as follows’: f 
"the genus: Porella, first established by Ditiehns and from a 
*Rev. Bryol. 19: 99. 1892. 
¢ Trans. Linn. Soc. 3: 238. 1797- 
