SPHENOPTERIS. 109 
would have been retained had there not been a Carboniferous fern 
of the same name. 
In looking at the specimen (V. 2242), Pl. VI. Fig. 2, and at that 
figured in Pl. VII. Fig. 1 (V. 2827), or the one with still more 
deeply lobed pinnules (V. 2327a), Fig. 10, p. 111, we seem to have 
two distinct species represented by these extreme forms. A careful 
examination of the several specimens included under the present 
species clearly demonstrates a gradual transition from one form to 
another, and I am unable to draw any satisfactory line between the 
various forms of fronds. The resemblance of certain specimens to 
species already described from other localities and horizons is pointed 
out in the descriptions of the individual fragments. Some of the 
specimens I was at first disposed to place under Sphenopteris 
Pichleri, Schenk,! as more perfect examples of that fern than 
appear to have been available when the species was instituted. 
It is extremely difficult to decide in certain cases whether the 
better course is to separate specimens by distinct names when they 
differ in the details of form shown by the ultimate segments, or to 
include them under one name. Neither plan will lead to final and 
satisfactory results so long as we have only fragments of sterile fronds 
and pinne to guide us. On the whole the inclusion of these frond 
specimens in S. /ttoni appears to me the preferable course, which 
may or may not be justified by the acquisition of more perfect 
material. In speaking of S. Pichleri, Schenk draws attention to 
the Hymenophyllaceous appearance of the pinnules; this same filmy 
character is well seen in some of the English forms of S. Fittonz, 
especially in the case of V. 2327a, shown in Fig. 10, p. 111. The 
chief differences between the specimens of S. /vtton?, which have 
some resemblance to S. Pichler, Schenk, also S. Cordai, Dunk.,? 
and the type specimen figured by Fitton, consist in the more 
divided pinnules and the more filmy nature of the lamina; the 
latter character is, however, not very trustworthy, as it may be only 
apparent and really due to differences in the rock matrix, thus 
being simply an accident of preservation rather than an original 
character. 
In addition to the species referred to below as resembling in 
a greater or less degree S. Lttont, there may be mentioned 
1 Paleontographica, vol. xxiii. p. 166, pl. xxix. figs. 2-5. 
2 Tbid. vol. xix. p. 210. 
