FOSSIL WORMS. ^ 171 



of sharply marked off segments, one within but less 

 than another, like the fully drawn-out parts of an 

 old-fashioned telescope. This species is very abun- 

 dant in the Woolhope beds. Ortonia (named after 

 Professor Orton) is a genus of abundant annelid 

 tubes, also free, which is peculiar to the Upper 

 Silurian rocks of North America. Tentaculites annu- 

 latus is the commonest of our British species ; T. 

 ornatus being perhaps the prettiest. The former is 

 more abundant in the Lower Silurian rocks at May 

 Hill and elsewhere, and the latter in the Upper. 

 The Wenlock shales are very rich in fossil worms, 

 Mr. Etheridge recording no fewer than thirty-five 

 species of all kinds, Dr. Hinde having added twenty- 

 four. Among the characteristic forms of these beds 

 are Trachy 'derma and Aranellites. 



No doubt there were ancient sea-worms resembling 

 Serpula, and it is possible some may have been inter- 

 mediate between it and the modern Sabella, which 

 latter is possessed of a leathery tube, often strength- 

 ened by adhering sand-grains. Thus, in the Upper 

 Silurian rocks above Ludlow, we meet with numerous 

 traces of a thin calcareous worm-tube, transversely 

 striated, and very ribbon-like, called Serpulites 

 longissimus. Trachyderma coriacea is still more like 

 a Sabella tube stiffened by a deposit of lime. Scolio- 

 derma serpulites is found in the rocks of the Wrekin 

 and in the holly-bush sandstones near Malvern. 

 Serpulites dispar is abundant about Ludlow, and also 



