THE JURASSIC FLORA OF SUTHERLAND. 661 



2. Matoninese. 



Laccopteris, Presl. 



The Sutherland specimens referred to this genus would no doubt be placed by some 

 authors in Saporta's genus Microdictyon, but as stated elsewhere, * the supposed 

 distinction as regards venation which led to the creation of the latter name does not 

 seem to me sufficiently important to justify generic separation. 



Laccopteris Dunkeri Schenk. (PI. I. figs. 5-13 ; PI. V. figs. 101, 101 A ; PI. VII. 



photo. 7 ; text-fig. 4.) 

 1871. Schenk, Paleeontographica, Bd. xix. p. 219, pi. viii. figs. 3-5. 



This species is abundantly represented by fragments of pinnules nearly all of which 

 are fertile ; in a few specimens part of a rachis or pinna-axis is preserved showing the 

 attachment of linear segments (fig. 6, PI. I. ; fig. 101, PI. V. ; photo. 7, PI. VI.). 

 While most of the pinnules have a breadth of about 5 mm., a few are 9 mm. broad. 

 The lamina is usually represented by a fairly thick layer of carbonaceous matter, and 

 the edges are often revolute, facts pointing to strong and thick pinnules. The 

 specimens illustrated in figs. 5, 8, 9, 10, PI. I., and photo. 7, PI. VI., despite the difference 

 in size, are included under one name because of the occurrence of intermediate forms 

 and their agreement as regards venation. Several specimens were treated with nitric 

 acid and chlorate of potash, but no sporangia were ibund. The sori are circular, with 

 a central receptacle (fig. 11 A, PL I.), as in the recent genus Matonia. 



Fig. 101, PL V., shows part of an axis 11 cm. long bearing alternate and sub- 

 opposite linear segments characterised by a prominent midrib. At first sight this very 

 obscure impression suggested a comparison with Nathorst's genus Pseudocycas,t but 

 closer examination revealed the presence of faint soral impressions (fig. 101 A). One of 

 the longest pinnules is seen in fig. 9, PL 1. ; this has a length of 6 cm. and a uniform 

 breadth of 4 mm., but it is broken across at each end and must have been much longer. 

 The sori, which occur in two rows, are generally preserved as prominent bosses with a 

 central pit (figs. 11,1 1 A). The repeatedly branched secondary veins form a reticulum like 

 that in the Inferior Oolite species L. polypodioides and in the specimens of L. Dunkeri 

 from the Wealden of Germany and Belgium. The venation of sterile segments is clearly 

 shown in text-fig. 4, and in the smaller pinnule in figs. 8, 8A. Fig. 12, PL I., shows the 

 repeatedly forked veins at right angles to the midrib of a fertile segment. The fertile 

 fragment represented in fig. 7, PL I., illustrates a fairly common manner of occurrence of 

 detached pinnules ; the coiled lamina may indicate immaturity. In some specimens 

 (fig. 10) the base of the lamina is slightly rounded, while in fig. 6 the attachment to the 

 axis appears to be by the whole base. The fragment shown in fig. 1 3 is identical, except 



* Seward (10), p. 360. See also Seward (99). t Nathorst (07). 



