Correspondence — J. A. Bartrum. 



425 



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Fig. 2 : Ckitsxacean Tracks in jSTew Zealand Tertiakies. — 

 This photograph, of natural size, depicts a portion of a large slab of 

 soft sandstone recently exposed in strata of Middle Tertiary age 

 along Beach Eoad, Auckland, New Zealand. The surface is covered 

 with feather-like or fern-like markings which represent casts formed 

 in the tracks left by some creature. The track (not the cast) coasists 

 of a median groove from which leaf-like imprints are given off on each 

 side. The groove, which has a semicircular section, is about 5 mm. 

 wide and pursues a gently sinuous course. Each appendage is about 

 13 mm. long, has a curved fi'ee margin, the curve havin-g a radius of 

 about 19 mm., and is overlapped by the corresponding margin of the 

 adjacent imprint at a distance varying in different appendages from 

 3'5 to 6 mm. The greatest width in each case is at about two-thirds 

 the distance from the point of origin. The axis of each appendage 

 forms with the median axis of the whole imprint an angle varying 

 between 35° and 75°, the greater angle usually being on the convex 

 side of a sinuosity in the median track. It is hard to say whether 

 the appendages are opposite'or alternate. 



Markings like those in Fig. 2 were formerly assigned to marine 

 algae (Chordophycese) or to annelids (JVereites), but the observations 

 of many naturalists, summarized and supplemented in Nathorst's 



