Oligochaeta ■ 17 a 



the matter of distribution. It was also shown that lineatus is evidently a 

 cosmopolitan form-, having been reported froni England, Ireland, Scotland, 

 Hebrides, North Russia, Denmark, Germany, France, Bohemia, Switzerland, 

 Terra del Fuego, and the coast of the New England States. It occurs commonly 

 under sea-weed on the shore in various parts of the globe. It has also been 

 found existing under fresh-water conditions. 



Lumbricillus, sp. (a). 



A collection from Pihumalerlcsiak island (Cockburn point). Northwest 

 Territories, July 15, 1916, contained thirty-three enchytraeids, of which thirty- 

 two were of similar size and general external appearance. These worms were 

 taken from the mud in a " water hole." Unfortunately, none of them are 

 mature and specific identification is impQssible. However, all of the specimens 

 examined in detail show the testes composed of a number of distinct lobes — 

 a character which has been regarded as diagnostic of the genus Lumbricillus. 

 Mention should be made of the fact that these specimens, while possessing the 

 divided testes, have straight setae — a feature which departs from the usual 

 definition of the genus Lumbricillus. 



Lumbricillus, sp. (b). 



The above mentioned collection from Pihumalerksiak island (Cockburn 

 point). Northwest Territories, July 15, 1916, also contained one specimen 

 which shows distinct differences when compared with the other individuals of 

 the same lot. The significant feature is the possession of sigmoid setae. It also 

 exhibits the divided condition of the testes and apparently belongs to the genus 

 Lumbricillus. However, the immaturity of the specimen prevents a specific 

 identification. 



General Considerations. 



Pigmentation. — In an earlier paper, the writer (1916 : 120) discussed the 

 presence of the pigmentation which occurs in all of the known glacier enchytraeids 

 and pointed out that it does not, seem possible to explain its presence on the 

 grotinds of low temperatures, since certain species in warmer latitudes show 

 pigmentation while others in frigid conditions show no indication of it. In this 

 connection, it is interesting to note that none of the specimens collected in 

 arctic Canada exhibit any marked pigmentation such as occurs in the above 

 mentioned glacier worms. The specimens of Mesenchytraeus johanseni n. sp. 

 show a heavy load of brownish-black pigment granules in all the chloragog cells 

 but none elsewhere. This is also true of the specimens of Lumbricillus sp. (a). 

 No pigmentation of any sort was observed in any of the other specimens. 

 Additional evidence is thus presented against the view that heavy pigmentation 

 of the internal organs in enchytraeids is directly correlated with frigid habitats. 



Seasonal Relations. — According to the field records of the collector, 

 some of the enchytraeids of this collection were found alive among moss roots 

 in dried-out stream beds in mid-summer. Possibly this is an indication of their 

 method of surviving drouth conditions of the summer season. At least it would 

 appear that these aquatic worms can tolerate a marked reduction of the water 

 in the surroundings. Another noteworthy feature is the very low temperatures 

 to which these worms are subjected during the winter months. The remarkable 

 resistance -of certain enchytraeids to frigid conditions has been discussed in 

 other papers (Welch, 1916; 1917b) and it is evident that the worms living in 

 arctic Canada are also successfully adjusted to long exposure at freezing 

 temperatures. 



