DESCRIPTION OF SPECIES. 21 



specimens, with the epidermis in place, the lateral nerves appear simple, but 

 when the plant has been subjected to maceration and pressure it is per- 

 ceived that they are really nerve-bundles, composed of two and sometimes 

 three fine thread-like nerves, which are usually so closely connected as to 

 appear to be a single nerve. I had often been struck, when viewing the 

 nerves on well-preserved impressions of the plant in which the epidermis 

 was retained, with the fact that they seem very vaguely defined, consid- 

 ering their apparent strength. Closer examination of other specimens 

 showed that this vagueness in the outline of the nerve is due to the tendency 

 of the component filaments to separate from one another and to spread out 

 under the influence of pressure and maceration. Plate V, Fig. 4, much 

 enlarged, shows this compound nature of the nerves, and also the insertion 

 of the lateral nerves, as well the way in which it is hidden by the thick 

 epidermis near the midrib. Plate V, Fig. 4 a, still more enlarged, shows 

 three filaments in the nerve-bundles. The fructification shown on Plate 

 IV, Fig. 1, if it be fructification, appears in the specimen seen by me in the 

 form of elliptical depressions placed on the midrib from the middle of 

 the leaf towards the base. They are drawn of natural size in Fig. 1 and 

 enlarged in Fig. 1 a. They are surrounded by a raised line which, sweep- 

 ing sharply around the ends of the depressions, continues double until a 

 divergence again takes place to embrace the next depression. Professor 

 Rogers says that on many specimens he found an irregular row of circular 

 depressions on each side of the midrib, and not unfrequently on the mid- 

 rib itself. m He states that they are placed at unequal intervals apart, and 

 at rather varying distances from the midrib. He considered the depressions 

 as indicating the positions of the sori, and I agree with him. I have not, 

 however, seen these depressions otherwise than in the form shown in Fig. 1. 

 They are rare, for I have seen but one distinctly-marked specimen. On 

 Plate IV, Fig. 1, in the three groups of nerves, a, b, c, I have depicted the 

 three principal modes in which the nerves depart from the midrib. They 

 are, however, not grouped in this way, but the different kinds alternate 

 with one another, and with single nerves. Macrotceniopteris magnifolia seems 

 to be most. nearly allied to Macrotceniopteris gigantea of the Rhae.tic of 

 Europe, and to Macrotceniopteris lata of India. Schenk's plant, as figured on 



