1889. J PROCEEDINGS OF THE NATIONAL MUSEUM. o5 



being the casts of worm-borings ; and there is nothing in the specimen 

 to indicate their vegetable origin. This form of cast is found in sandy 

 argillaceous deposits all through the sedimentary rocks. 

 Type in the Museum of the Geological Survey of Canada. 



Planolites incipiens Billings. 

 I'ahrophyctin hic'qjiens Billings, 1861. Bull. Geol. Survey Canada, p. 3. 



This character of worm-boring is common in the sandy shales near 

 Swanton, and at Parker's Quarry, Georgia, Vermont. It is associated 

 with Olenellus asaphoides. It is impossible to .determine whether the 

 trails on the slate were made by the same species of animal as that 

 making the trails referred to P. congregatus. As the two forms have 

 received specific names they are retained for the present. 



Type in the Museum of the Geological Survey of Canada. 



Helminthoidichnites Fitch. 



Helminthoidichnites Fitch, 1850. Trans. N. Y. State Agric. Soc. for 1849, p. 868. 

 Compare Nemertites Nicholson, 187:5. Proc. Roy. Soc, London, p. 289. 



Helminthoidichnites marinus Emmons (sp.). 



Gordia marina Emmons, 1844. Taconic System, p. 67, pi. 1, fig. 2. — Idem, 1846. 



Agric. N. Y., vol. 1, p. 68, pi. 14, fig. 2.— Idem, Hall, 1847. Pal. X. Y.,vol. 1, 



p. 264, pi. 71, figs. 1, 2. 

 Palwophycus rectus Fitch, 1850. Trans. N. Y. State Agric. Soc. for 184',), p. 862. 

 Compare Fucoides ftexiiosa Emmons, 1844. Taconic System, pi. v, fig. :!. 

 Helminthoidichnites tenuis Fitch, 1850. ■Traus. N. V. State Agric. Soc. for 1849 ; p. 866, 



figure in text. 



Dr. Fitch proposed the genus Helminthoidichnites for tracks resem- 

 bling those of worms, and figured this species as a very narrow trail on 

 an arenaceous shale. I have seen fragments of a similar trail in the 

 arenaceous slates of the Olenellus zoue, and also in the Upper Cam- 

 brian shales of the Grand Canon of the Colorado, Arizona. Those from 

 the latter locality afford the best illustration, and a figure is given of a 

 small portion of the surface of the arenaceous shale, showing the trail 

 upon it. 



This type of boring or trail is very abundant in the purple, green, 

 and dark slates, and in the arenaceous shales of the Olenellus zone. 

 Similar trails ma}' have been made by many different species during 

 all the geologic epochs down to the present day. 



Nat. Mus. Cat, Invt. Foss., No. 18359. 



Cruziana d'Okbigny. 



Bilobites DeKay, 1823. Am. Lye. Nat. Hist., New York, vol. 1 pp. 45-49. 



Not Bilobites Linn., 1775. 



Cruziana d'Orbigny, 1842. Voyage d'Amerique Mcrid., in. 



Eusophycus Hall, 1852. Pal. N. Y., vol. 2, p. 23. 



Cruziana sp. .' 

 A careful examination of a large scries of specimens of the trails and 

 burrows referred lo Cni:i<nitt. IV.nn ;i single layer of sandstone, leads 



