Phylum III. VERMES. Worms.' 



Bilaterally symmetrical animals with unsegmented or uniformly segmented, and 

 usually elongated bodies having a distinct body cavity. Segmented lateral appendages 

 wanting. A dermal muscular sysj^em and paired excretory 

 canals (water-vascular System) present. 



Of all the larger divisions of the animal kingdom, none 

 is so poorly adapted for preservation in the fossil State as 

 the Worms, whose bodies are as a rule entirely destitute 

 of hard parts. 



All Worms are bilaterally symmetrical, and dorsal and 

 ventral surfaces are clearlj^ differentiated. The unsegmented 

 Worms (Vermes proper) have either fiat or cylindrical bodies, 

 and are accordingly distinguished as Platyhelminthes or 

 Fiat Worms, and Nemathelminthes or Round Worms. But 

 with the exception of the Cambrian genus Amiskwia (Fig. 

 213), supposed to be allied to the Recent Sagltta, and a few 

 rare parasitic forms discovered in Carboniferous insects, or 

 in Tertiary insects enclosed in amber, neither of these classes 

 is represented in the fossil State. 



• The segmented Worms, or Annelida, are characterised 

 by a division of the body into metameres, which, although 

 primitively alike, do not always remain homonomous. 

 They have a brain, a circumoesophageal ring, a ventral chain 

 of ganglia, and a vascular System. The body is more or less elongated, and 



^ Literature : Fander, O. H., Monographie der fossilen Fische des silurischen Systems des 

 russisch-baltischen Gouvernements, 1851. — Ehlers, A'., Die Borstenwürmer (Annelida Chaetopoda). 

 Leipzic, 1864-68. — Idem, Über fossile Würmer aus dem lithographischen Schiefer in Bayern. 

 Palaeontogr. , 1868, vol. xvii. — Olaparede, Vi'., Recherches sur la structure des Annelitles sedentaires, 

 1873. — Newherry, J. *S'., Palaeontology of Ohio, vol. ii. part 2, 1875. — Ilinde, G. J.. On Conodonts 

 from the Chazy and Cinciunati Groups ; and on Annelid Jaws from the Cambro-Silurian, Silurian, 

 and Devonian Formations in Canada, and from the Lower Carboniferous in Scotland. Quar. Journ. 

 Geol. Soc, 1879, vol. xxxv. — Ulrich, E. 0., Journ. Cinciunati Soc. Nat. Hist., 1879, vol. i. — 

 Hitide, G. J., On Annelid Jaws from the Wenlock and Ludlow Formations of the West of 

 England. Quar, Journ. Geol. Soc, 1880, vol. xxxvi. — Etheridge, R.,jun., British Carboniferous 

 Tubicolar Annelida. Geol. Mag., 1880, vol. vii. — Nathorst, A. G., On the Tracks of sonie 

 Invertebrate Animals and their Palaeontological Significance. K. Svensk. Vetensk. Akad. Handl., 

 1881-86, vols. xviii., xxi. — Ilinde, G. J., On Annelid Remains from tlie Silurian Strata of the Isle of 

 Gotland. Bihang tili K. Svensk. Vetensk. Akad. Handl., 1882, vol. \n.~Zittel, K. A., and 

 Rohon, J. V., Ueber Conodonten. Sitzber. Bay. Akad. Wiss., 1886, vol. xvi.—Clarke, J. M., 

 Annelid Teeth from the Lower Portion of the Hamilton Group, New York. Sixth Annual Report, 

 N.Y. State Geologist, 1886. — Rovereto, G., Studi monografici sugli Annelidi fossili. Palaeont. Ital., 

 1904, vol. X.— Walcott, O. D. , Middle Cambrian Annelids. Smithson. Mise. Coli. ,1911, vol. Ivii. No. 5. 



135 



Fig. 213. 



AmislauiM sayltti- 

 formis Walcott. Mid- 

 dle Carnbrian; British 

 Columbia. Flatt«ned 

 specimen, x ^/i (after 

 Walcott). 



