Oligochaeta 13 A 



DEFINITION. Length, 6-3-13 mm. Diameter, about 0-45 mm. Somites, 

 40-51. Colour of alcoholic specimens light brown. Prostomium blunt; round; 

 smooth. Setae 3-5 per bundle in both lateral and ventral rows, fewer at 

 extremities; all in bundle about same size; distinctly sigmoid, distal points 

 recurved. Clitellum slightly developed; on 12-13. Lymphocytes scanty; 

 ovoid. Brain about one and one-half times longer than wide; anterior and 

 posterior margins slightly concave; lateral margins divergent caudad; two 

 pairs of supporting strands from posterior part. Peptonephridia present; one 

 dorsal and one ventral strand; dorsal strand arising from digestive tract in 5 

 and extending caudad, thickened at origin, in contact with wall of digestive 

 tract to posterior part of 7 and extending under intestinal diverticulum, giving 

 off branches into coelom in 6; ventral strand also in contact with walls of digestive 

 tract in 3, 4, and 5, tubular, rather thick walled, apparently no branching but 

 merely irregular folding. Oesophagus enlarging abruptly into intestine in 

 anterior part of 8. Intestinal diverticulum of- peculiar structure; completely 

 surrounding digestive tract in 7; thin walled; large internal cavity; very few 

 folds of lining; no evidence of internal tubules; longitudinal, mid-dorsal partition 

 separating internal space into right and left parts; connection with digestive 

 tract very obscure and not definitely determined. Dorsal blood-vessel arising 

 in 8. Nephridia with anteseptal part as mere nephrostome; postseptal part 

 large; efferent duct arising from ventral surface of latter near septum. Spermi- 

 ducal funnel but little longer than wide; with thin, reflected collar; attached 

 end merging gradually into sperm duct for some distance. Sperm duct in 12 

 only; much coiled. Penial bulb of simple lumbricillid type; small, maximum 

 diameter only about one and one-half times greater than that of ventral nerve 

 cord in same transverse section; cells of one kind only in bulb. Spermathecae 

 with one group of very small glands at ectal opening; duct expanding gradually 

 into globular ampulla; ental end of ampulla joining corresponding part of 

 opposite spermatheca, dorsad of digestive tract, to form a common duct leading 

 into digestive tract in posterior part of 5; diverticula lacking. 



Henlea, sp. (a). 



Among the specimens collected at Pihumalerksiak island (Cockburn point) , 

 Northwest Territories, July 15,' 1916, from between moss roots, one specimen 

 was found which, though too immature to identify to species, showed clearly 

 the characters of the genus Henlea. There are some indications that this 

 specimen may be an immature Henlea nasuta (Eisen). 



Henlea, sp. (b). 



The collections from Bernard harbour included one bottle containing four 

 specimens from the mud of a shallow tundra pond, May 31, 1916. Two of the 

 specimens were hopelessly deteriorated while the other two were immature, 

 thus making specific identification impossible. The two best preserved speci- 

 mens were sufficiently developed to make it certain that they belong to the 

 genus Henlea. There is some evidence that these specimens are immature 

 examples of the same form listed provisionally on a preceding page as Henlea 

 tenella (Eisen). 



Enchytraeus hyalinus, var. 



A collection from Pihumalerksiak island (Cockburn point), Northwest 

 Territories, July 15, 1916, contained eighty-seven specimens, of which about 

 one-fifth were mature. These enchytraeids were collected among moss roots, 

 and described in the field notes as " white worms," referring, no doubt, to the 



