18 



HISTORICAL GEOLOGY 



(Sea-cucumbers) are soft bodied, with leathery covering, tentacles 

 around the mouth, and skeletons of scattering limey spicules. 



B 



Fig. 8 

 Modern Echinoids ("Sea-urchins"), one with spines in position. (After 

 Coe, from Schuchert's "Historical Geology," permission of John Wiley 

 and Sons.) 



V. Vermes or Worms include a large group of forms more 

 complex in organization than the preceding groups. Some are 

 segmented and others are not. Since hard parts are very rarely 

 developed, the Worms are of no great importance as fossils, their 



Fig. 9 

 Bryozoans: A, portion of modern colony seen from above (xl5); C, an 

 individual expanded; D, fossil form. A-C after Verrill and Smith; 

 D, from Ulrich. (From Shimer's "Introduction to the Study of Fossils," 

 permission of The Macmillan Company.) 



presence usually being indicated by trails, burrows, or tubes made 

 in mud or sand. 



VI. Molluscoids, as the name suggests, bear a resemblance 

 to the Mollusks. They differ from the Anthozoans, Echinoderms, 



