PLATE XXVII. 



Helminthoidichnites marintjs. 



Fig. 1. A common form of burrow or trail, that occurs on the surface of the slate, associated with 

 the medusae. It has the appearance of a number of narrow trails made on a broad trail, 

 such as is represented by fig. 2. 



Fio. 2. Abroad, smooth trail on the surface of the slate. 



Fig. 4. Cast of a boring in which the mud was pushed back by the animal that made it. 



Fig. 5. Narrow trails as they occur on the surface of the slate. 



All of the above occur in the same band of slate with D. asteroides. 



Dactyloidites asteroides (p. 41). 



Fig. 3. A small specimen showing traces of the central disk. 



Fig. 6. A specimen preserving the exumbrella lobes and a peculiar flattening of the subumbrella 

 lobes. 



158 



