352 FILICALES [CH, 



Some Carboniferous fronds with short and small pinnules of 

 the Pecopteris type, bearing sori composed of a small number of 

 sporangia, have been assigned by Grand'Eury and other authors 

 to the Gleicheniaceae ; the same form of sorus is met with 

 also on fronds with Sphenopteroid segments. The former is 

 illustrated by Oligocarpia Gutbieri^ and the latter by 0. Brong- 

 niarti described by Stur and by Zeiller^. Zeiller has described 

 the circular sori of Oligocarpia (fig. 270, B) as consisting of 

 three to ten pyriform sporangia borne at the ends of lateral 

 veins and possessing a complete transverse annulus, but Stur* 

 believes that the annulus-like appearance is due to the manner 

 of preservation of exannulate sporangia. In this opinion Stur 

 is supported by Solms-Laubach* and by Schenk*. Despite 

 an agreement between Oligocarpia and Oleichenia, as regards 

 the form of the sori and the number of sporangia, it is not 

 certain that the existence of a typical Gleicheniaceous annulns 

 has been proved to occur in any Palaeozoic sporangia®. 



From Upper Triassic beds of Virginia, Fontaine has figured 

 several fronds for which he instituted the genus Mertensides'' . 

 The habit, as he points out, is not dichotomous, but the sori are 

 circular and are said to be composed in some species of four to 

 six sporangia. No satisfactory evidence is brought forward in 

 support of the use of a designation implying a close relationship 

 with recent Gleichenias (sect. Mertensia). One of the species 

 described by Fontaine was originally named by Bunbury 

 Pecopteris bullatus^, the imperfect type-specimen of which is 

 now in the Museum of the Cambridge Botany School. In the 

 form of the frond, the thick rachis, and in the pinnules this 

 Triassic species resembles Todites Williamsoni, but the re- 

 semblance does not extend to the sori. Two of Fontaine's species 

 are recorded by Stur from Austria^, but he places them in the 

 genus Oligocarpia and includes them in the Marattiaceae. 



1 Goeppert (41) PI. iv. figa. 1, 2. " Zeiller (88) A. PI. xi. figs. 3—5. 



3 Stur (85) A. p. 128. ■> Solms-Laubach (91) A. p. 146. 



» Sohenk (88) A. p. 30. 



' Dr Scott tells me that an examination of Dr Zeiller's specimens led him 

 to agree with the latter's description of the annulus of Oligocarpia. (A. C. S. ) 

 ' Fontaine (83) Pis. xv.— xix. 

 8 Bunbury (47) PI. n. fig. 1 ; Seward (94=) A. p. 189. » Krasser (09) p. 16. 



