SYSTEMATIC POSITION OF A GIGANTIC EARTHWORM. 65 



The fact that these animals will live in soil impregnated with brackish water is 

 highly interesting ; we know of two other species, however, which live among decaying 

 vegetable matter cast up by the sea, and therefore quite salt — these are Pontodrilus 

 littoralis and Pontodrilus marionis \ Such facts may possibly help to get over the great 

 difficulties connected with the geographical distribution of these animals. It was formerly 

 believed that Earthworms and their eggs were killed by immersion in salt water, and it 

 was presumed, therefore, that the facts in their geographical distribution would be of 

 particular value, inasmuch as the species would be indigenous to the countries where 

 they were found 2 , and the presence, in two countries separated by the sea, of the same, 

 or at least closely allied genera, would furnish very strong evidence in favour of a land 

 connection having existed formerly between the two regions. Since we find closely 

 allied species, let alone genera, in widely separated countries 3 , the occurrence of which 

 is hardly explicable by the interference of man, the facts stated above seem to suggest 

 that the cocoons of Earthworms may, after all, be transported across the sea on floating 

 timber. 



External Characters. 



The extreme length of Microchceta rappi it is difficult to state with certainty; 

 during its lifetime the animal elongates and contracts itself so very much ; the accom- 

 panying drawing (PL XIV.) represents very fairly the average length of the animal, 

 which appears to be between 4 and 5 feet. When killed and placed in spirit it 

 contracted itself to 38 inches. The colour when living is admirably illustrated by 

 Mr. Smit's drawing, which was made from the living animal. 



The dorsal surface is dark green, the colour being especially bright for a space of 

 about 3 inches near the anterior end of the body, elsewhere it passes into a duller 

 greenish violet ; the ventral surface is of a flesh-red ; when placed in spirit the colour 

 after a time faded to a dull grey, but the bright green patch in front, corresponding in 

 fact to the clitellum, remained for a very long time. 



The setas are arranged in two pairs as in the common British Lumbricus terrestris, 

 and nearly equidistant from each other. As pointed out by Rapp they are extremely 

 small and inconspicuous, and tend to disappear altogether at the anterior end of the 

 body ; this makes it extremely difficult to fix accurately the boundaries of the segments 

 in this region, since, as will be pointed out presently, the mesenteries have lost their 



1 Perricr, Arch. d. Zool. Exp. t. ix. 



2 Except, of course, such anomalies as were evidently caused by the agency of man, e. g. the occurrence of 

 Perichceta in hothouses in England and the Jardin des Plantes at Paris ; these specimens have, no doubt, been 

 imported along with plants from foreign countries. 



3 As an instance of this, the distribution of Acanthodrilus may be adduced ; there are seven species of the 

 genus known — three from Africa, one from Madagascar, two from New Caledonia, and one from Kerguelen 

 Island, and another, which I hope to describe shortly, came in the same box with the large Earthworm 

 described in the present paper. I have also received examples of three distinct species from New Zealand. 



