NOTE ON NILSSONIA MUCEONJTUM (DE VIS). 231 



NOTE ON NILSSONIA MUCRONA TUM (DE VIS) 



From the Cretaceous of Western Queensland. 



By a. B. WALKOM, B.Sc, 



Assistant Lecturer in Geology, The University of Queensland, and 

 Honorary Palaeontologist to the Queensland Museum. 



(Plate XXIV.) 



The present note is the result of an examination of the specimen described 

 by the late Mr. De Vis as Pterophylhim nmcronatum, sp. nov., in the Annals of 

 the Queensland Museum.^ 



The description and figures of De Vis do not correspond with one another 

 and I was permitted, through the courtesy of the Director of the Museum, to 

 examine the original specimen (No. F15/967) and to undertake its re-description. 



DESCRIPTION OF THE SPECIMEN. 



The specimen is a single incomplete pinnate frond ; it has a length 

 (incomplete) of 12-5 cm. and is 5-8 cm. wide at its lower end and 4-8 cm. at the 

 upper end. 



The pinna? are alternate, fairly uniform in shape and size, and are close 

 together ; they are from 2-6 cm. to 3 em. long and 6 to 7 nun. wide ; they are 

 inserted on the upper surface of the rachis which has a width of from 1-5 to 

 2 mm. The pinnae narrow very slightly near their junction with the rachis ; the 

 upper margins of the pinna- are straight and make a wide angle (about 80°) 

 with the rachis ; the lower margins are at first parallel with the upper, but they 

 curve upwards rather suddenly at a distance of about 2-5 cm. from the rachis, 

 forming truncated pointed tips to the pinna?. 



The venation is not well defined, but as far as can be seen there are 

 10 to 12 veins per pinna and they appear to be very slightly divergent. (See 

 Plate, figs. 3 a and h.) 



OBSERVATIONS. 



The specimen shows the frond viewed from the lower surface, but over 

 the greater part the actual material of 'the pinnre has been removed, leaving the 

 impression of the upper surface. At a few places the material replacing the 

 pinna? is preserved and it is on these that the venation can best be observed. 



The rachis projects markedly above the level of the remainder of the 

 frond and so it hides, for the most part, the manner of attachment of the pinnae 

 to the rachis. Fortunately in one or two places the rachis is broken away and 

 the pinnaj are seen to have continued almost to the middle of the rachis before 

 joining it. {See Plate, fig. 2.) This method of attachment at once shows that 

 the specimen was incorrectly placed in the genus Pterophyllum, where the 

 attachment is lateral. 



1 Ann. Q'land Mus. No. 10, 1911, p. 1, pi. ii. 



