372 Messrs Forbes and Goodsir on the Natural History 



the rest of the animal, being of a bright scarlet. It is so 

 slightly affixed to the body as to break off on the least touch, 

 and in only one or two cases did we find it attached, and then 

 it broke away immediately on the removal of the animal. 



On keeping the Echiurus alive in a vessel of sea-water, it 

 was continually changing its form, swelling itself out in va- 

 rious parts so as to assume very strange and eccentric shapes- 

 If a fresh supply of salt water was poured into the vessel, it 

 would on a sudden become very vivacious, starting up to- 

 wards the surface, and swimming with spiral contortions in 

 the manner of an annelide. Then it would sink to the bot- 

 tom of the vessel, and swell itself out with water. 



The Echiurus, like the Thalassema, was first figured and 

 described by Pallas, who obtained it from the coast of Bel- 

 gium. He gave a most accurate general representation of it, 

 but strangely omitted the true proboscis ; and by all writers 

 since his time the sheath has been described as a proboscis 

 not only in this case, but in the descriptions of most of the 

 other Thalassemaccw. 



Montagu first perceived the true relation of the Thalas- 

 sema, and remarks in his paper that it should immediately 

 precede Holothuria. This view of its position was also held 

 by Cuvier, and more lately by Brandt. Lamarck, however, 

 placed the Thalassema and Echiurus in his first division of 

 annelides, characterized by having no feet, and including the 

 families Hirudines and Echiurete. In the hitter, associated 

 with the earth-worm and cirratulus, we find these animals be- 

 fore us. Many zoologists since his time have looked upon 

 them as worms, but the structural details which follow will 

 shew that their relation to the annelides is one of analogy 

 and not of affinity, and that their true position is among the 

 Echinodermata in the order of Vermigrada or Sipunculidce* 



Echiurus — Digestive System. 



The digestive tube commences by a mouth of a rounded 

 form, very small in the state of contraction, funnel-shaped 

 when dilated. The oral orifice is continuous with a canal 



* See Forbes's British Echinodermata. 



