366 OLIGOCHAETA 



curious, from certain districts of North America. In the 

 tropics these animals seem to be on the whole less abundant 

 than in more temperate climates. But this deficiency of indi- 

 viduals is counterbalanced by the greater variety of generic 

 and specific types. From tropical Africa, little explored as it 

 has been from this point of view, no less than thirty genera, 

 including about ninety species, have been recorded ; whereas 

 in Great Britain only four genera and seventeen species occur, 

 and in all probability but few remain to be discovered. The 

 vertical range of these Annelids is also considerable. Several 

 species have been met with in Europe and elsewhere at an alti- 

 tude of 10,000 feet. 



For the bulk of the species the term earthworm is an accurate 

 description of their habitat. But there are not a few which 

 occasionally or habitually prefer other localities. The -genus 

 Allurus is equally at home in soil or in water ; I have taken it 

 in the fast - flowing river Plym in Devonshire. The genus 

 Acanthodrilus includes a few species which have at present only 

 been met with in water ; A. schmardae comes from fresh water 

 in Queensland, A. stagnalis from ponds in South America ; A. 

 dalei is like Allurus in that it is to be found both on land and 

 in streams and ponds. The Enchytraeidae are just as amphibious ; 

 Criodrilus and Sparganophilus appear to be purely aquatic. A 

 more curious locality for a creature that is so characteristically 

 terrestrial is the margin of the sea. For a. long time a species 

 belonging to a peculiar genus Pontodrilus has been known from 

 the shores of the Mediterranean in the neighbourhood of Nice. 

 It lives there among seaweed above high-water mark, but it must 

 at least occasionally be splashed by the waves. Another species 

 of the same genus occurs on the coast of Brazil and some of the 

 West Indian islands ; Pontoscolex corethrurus and Diackacta 

 littoralis were described by Schmarda 1 from the shores of 

 Jamaica. The former species is one of the most widely distri- 

 buted of earthworms, and, except in this particular part of the 

 world, has been always taken on the land far from the sea. There 

 are also partly marine forms among the Tubificidae ; Clitellio 

 arenarius is common on our coasts. 



While there are several kinds of earthworms that are thus 

 met with in fresh water, others will live for some time submerged 



] Neue wirbellose Thiere, Leipzig, ii. 1861, p. 11. 



