208 THE LATE DR. NEWELL ARBER: CRITICAL STUDIES 
B. Major Pinnules. 
1886-83. Neuropteris acuminata, Zeiller, Flore Foss. Bass. Houill. Valenciennes, p. 255, 
pl. 41. fig. 4. 
1906. Neurodontopteris obliqua, Gothan, in Potonié, Abbild. und Beschr. Foss. Pflanzen, 
Lief. iv. No. 68, text-figs. 2B, 4, 5, pl. unnumbered, following p. 11, fig. B. 
1907. Mixoneura obliqua, Zalessky, Bull. Com. Géol, St. Pétersbourg, vol. xxvi. No. 134, 
— p. 479, pl. 19. figs. 2 & 10. 
1910. Neuropteris acuminata, Axber, Proc. Yorks, Geol. Soc. vol. xvii. pt. ii. p. 138, pl. 17. 
fig. 3. 
1911. Neuropteris inpar, Kidston, Mém. Mus. R. Hist. Nat. Belgique, vol. iv. p. 83, 
pl. 8. figs. 2, 3, 3a. 
C. Major and Minor Pinnules. 
1837. ? Neuropteris heterophylla, Lindley & Hutton, Foss, Flora, vol. iii. p. 90, pl. 183. 
1893. Neurodontopteris inpar, Potonié, Jahrb. k.-preuss. geol. Landesanstalt für 1892, 
p. 1, pl. 1. figs. 1, 2, 4. 
1906. Neurodontopteris obliqua, Gothan, in Potonié, Abbild. und Beschr. Foss. Ptlanzenr, 
Lief. iv. No. 68, pl. unnumbered following p. 11, fig. B. 
1911. Neuropteris impar, Kidston, Mém. Mus. R. Hist. Nat. Belgique, vol. iv. p. 83, 
pl. 8. fig. 1. 
Remarks on the Synonymy of Neuropteris obliqua, Brongn. 
Neuropteris obliqua (Brongn.) is a species of Coal-measure frond which 
has already caused considerable trouble and confusion. We are as yet 
probably not at an end of our difficulties in this respect. These fronds were, 
like those of certain other species of the genus, dimorphic. On one side of 
the frond we may find pinnæ composed of a large number of small tri- 
angular pinnules here termed minor pinnules, while, on the other, simple, 
large, ovate-lanceolate leaflets may occur, here called the major pinnules. 
Or, again, the pinnæ may consist solely of major or minor pinnules. The 
minor pinnules, which were the first described portions of these fronds, are 
often typically Odontopteroid. They are often decurrent, and, further, a 
considerable portion of the lateral nerves arise directly from the rachis and 
not from the median nerve, which is weak. They are very little arched, but 
are sinuous in their course, each nerve dichotomising two or three times. 
The sinuous course of the nerves necessitates unequal intervals of lamina 
between the nerves, and this feature is highly characteristic of this species. 
Did the evidence end here, this species would be more correctly classed 
with Odontopteris than Neuropteris, especially on account of the attachment 
of the pinnules and the origin of the lower lateral nerves. It has, in fact, 
been placed in that genus by more than one authority, while Potonié 
expressed the facts by suggesting a new genus Neurodontopteris, which, 
however, has not been adopted by other workers. Similar resemblances 
occur to other genera, such as Alethopteris and Callipteris. In fact, the 
definitions of these form-genera break down over such cases as this, and it is 
purely a matter of convention in which genus this species is placed, 
