Oligochaeta 11 A 



INTESTINAL DIVERTICULUM. Structurally, the intestinal diverticulum in 

 these Collinson point specimens resembles very closely those in Henlea maderata 

 Welch and Henlea tubulifera Welch. The writer pointed out in an earlier paper 

 (Welch, 1914 : 160) that a similar type of structure is reported for the intestinal 

 diverticulum in the genus Hepatogaster 6ejka. In fact, Cejka (1910) uses this 

 type of structure as one of the distinguishing characters of Hepatogaster. How- 

 ever, since the Collinson poinl^ material lacks the canals in the intestinal epithe- 

 lium and since the peptonephridia and spermathecae differ from those described 

 for that genus, this species is herein recorded as belonging to Henlea. 



This organ arises from the posterior end of the oesophagus in 8 and is 

 reflected cephalad, closely investing the latter for almost the entire length of 

 the somite. It occupies approximately one-half of the body-cavity in 8. A 

 deep, narrow, longitudinal depression on the mid-dorsal side partly encloses the 

 dorsal blood-vessel. A smaller, longitudinal depression on the mid-ventral 

 surface partly encloses the ventral blood-vessel. The organ is largely composed 

 of a series of branching, longitudinal, thick-walled tubules closely crowded 

 together, which unite near the caudal end of the diverticulum and open into the 

 lumen of the digestive tract through a few larger tubes. 



It might be mentioned that Friend (1914 : 151-153) lists Henlea tenella 

 under a heading " cesophageal glands absent," but, since the English record is 

 uncertain, this statement is disregarded. 



PENIAL BULB. The penial bulbs are small, being but little thicker, in 

 transverse section of the body of the worm, than the adjacent muscle-layer of 

 the body-wall. They are simple in structure, conforming to the lumbricillid 

 type. Each is composed of but one set of gland cells and is covered by a well- 

 developed muscle-layer. The sperm duct extends well into the bulb to unite 

 with a distinctly differentiated penial lumen. In the description of the species 

 given by Michaelsen (1900 : 70), the statement is made that the penis is much 

 smaller than the sperm funnel but it is uncertain what part or how much of the 

 penial bulb apparatus is referred to. If this statement applies to the whole 

 penial bulb, it is not true for the American specimens since the penial bulb is 

 as large as the sperm funnel although but little larger. 



SPERMATHECAE. The original description by Eisen (1879 : 17) contains no 

 mention of any connection of the spermathecae with the digestive tract, and 

 his accompanying figures (PL III, 5g; PL IV, 5m) seem to indicate that they 

 end blindly, being very much narrowed at the ental end. Since the ental 

 extremities of the spermathecae in the Collinson point specimens are very much 

 reduced in diameter, the writer is inclined to suspect that Eisen overlooked the 

 very inconspicuous alimentary connection, or else examined immature speci- 

 mens, since there is evidence that the connection with the digestive tract is 

 one of the last features to be completed in the development of the spermatheca. 

 Eisen also states that "A form with the receptacle bent at the top and some- 

 what longer could perhaps be separated as a variety: elongatus (PL IV, fig. 5m). 

 This variety was found in Norway near Tromso, together with Neoenchytraeus 

 Ratzelii, and may be considered as a local variety or a beginning species." This 

 " variety " was also probably described from immature specimens or else the 

 alimentary connection was overlooked. Judging from the above description 

 and an examination of the original figures, there seems to be no grounds for 

 establishing such a variety. 



DISTRIBUTION. The specimens studied by Eisen and classified as Henlea 

 tenella were collected on Solowetski island in the White sea (65 n. lat.), at 

 Tromso, Norway (about 69 n. lat.) and at " Sapotschnaja Korga, Jenissej," 

 Siberia (71 41' n. lat.). Aside from an uncertain record by Friend (1912 : 585-6) 

 of its occurrence in England, no other records appear in the literature, and it 

 thus appears that the species, as known at present, is Arctic in its distribution. 

 Although widely removed geographically from the known Old World localities, 

 this species apparently exists under similar conditions in arctic America. 



