FERNS— PECOPTERIDE.E—PEGOPTERIS. 89 



ultimate lateral piniire Ijeing succeeded l^y A-ery small Y)inna3 or pinnatifid 

 pinnules. An intermediate stage is seen in the illustration of No. 3179/ PI. 

 XXVlil, Fig. 2, while the pinnatifid higher stage is shown in PI. XXX, 

 and PI. XXXII, Fig. 1, the enlarged details of the pinnules being given in 

 PL XXX, Figs. \a-c, though the pinnse are often more obtuse. Still lower, 

 however, than the pinnse shown in the large slab, the lateral pinnae become 

 considerably broadened, the pinnules also assuming- a crenulate phase, 

 though both the outlines and the details are conformable to the type. 



The characters of the fertile pinnae, as noted in the above description, 

 are quite uniform. When first appearing in specimens showing the upper 

 surface of the lamina, the sori appear as small pustular, noncontiguous 

 elevations, arranged in a ro^^' nearly midway between the midrilj and the 

 margin in the pinnules and lobes, which are slightly reduced and rather 

 more coriaceous than in the sterile pinnas. In Fig. 2, PI. XXXI, of No. 

 3097,^ in the Lacoe collection, chosen for illustration on account of its 

 better adaptation to photography, the sori are expressed faintly through the 

 fertile portion of the fragment. At a later stage they seem to occupy most 

 of the sui-face of the pinnule, from beneath which, when crushed, as is 

 usually the case, the sharp apices of the sporangia may protrude in a man- 

 ner observed in the g-enus Scohcopterls Zenk. PL XXXII, Fig. 2, shows a 

 fragment from a portion of a frond which is also referable to this species, 

 probably corresponding nearly to the position seen in the large slab, PL 

 XXIX. It represents the upper surface of the pinnules, a portion of which 

 show traces of the sporangia. 



It is very rarely possible to gain an adequate idea of the spoi'angia when 

 the lower surface of the pinna is exposed, since they are in every case badly 

 crushed. Still it seems fairly certain that the sporangia are usually in 

 groups of four attached by the obtuse base, the upper, pointed, free ends 

 being erect, on which account they are generally broken down or matted in 

 the impression so as to obscure the arrangement. Fig. 3« on PL XXXI 

 will serve to illustrate the appearance of the sporangia in one of the speci- 

 mens which I somewhat doubtfully refer to this species, although the view 

 (ventral surface) of the pinnule presented is not suitable for detailed illus- 

 tration. 



'Identified by Professor Lesquereux as Pecopteris cUnioni; in the Lacoe collection. 

 -Identified by Professor Lesqnereux as Alethopteris ambigita. 



