34 ON CERTAIN VERMIFORM FOSSILS. 



PLATE IV. 



Fif). 1. Narrow, furrowed track of Kroyera arenaria: a, farrow; 5, h, slight 



lateral ridges. 

 Fig. 2. Variety of ditto regularly zig-zagged. 



Fig. 3. Track exhibiting a rounded ridge, a; with a narrow lateral furrow, b. 

 Fig. 4. Ditto, with the ridge broken up into nodules ; «, groove. 



PLATE V. 



Eeduced view of a slab, bearing nodulous tracks, in the possession of 

 Blr. Wood ; «, «, nodules ; 6, b, points where one fold or winding cuts 

 through another. 



PLATE VI. 



Fig. 1. View of a slab, exhibiting nodulous tracks, with the cast of the burrow 

 partially removed : «, a, portions of the tracks, with the cast removed, 

 showing impressions of the nodules ; J, ditto, ditto, showing one track 

 passing through another ; c, c, supposed sinkings or perforations of 

 small crustaceans; (7, a small track terminating in similar perforations, 

 e, e; f,f, septa dividing the nodules. 



Fig. 2. Side view of a portion of the cast of the same track, showing the nodules, a. 



PLATE VII. 



Reduced view of a slab in the Newcastle Museum, exhibiting tracks : 

 a, large depressed, grooved track ; 5, groove of ditto ; c, c, c, small 

 furrowed tracks passing over the large grooved species in various direc- 

 tions. 



PLATE VIII. 



Fig. 1. View of a slab, of the natural size, in the possession of Mr. Howse, bear- 

 mg small, much convoluted variety of the large grooved track : a, 

 central ridge. 



Fig. 2. Portions of a variety of large grooved track of the size of nature, show- 

 ing a central, elevated area and transverse striae or ridges : o, central 

 elevated area ; 6, central groove of ditto ; c, c, lateral areas ; f7, portion 

 of another track exhibiting the central elevated area broken up into 

 nodules, e, e. 



