ENCHYTRAEIDAE 



263 



development of the male cells, and the compact, ovoid, and encapsuled penial body with 

 characteristic structure are absent, and are represented by the less specialized con- 

 ditions found in Enchytraeus. 



The specific name is taken from the Greek koXttlt-i]^, dwelling on a bay (/coXttos). 



Genus Michaelsena, Ude 



Michaelsena monochaeta (Michaelsen) (Fig. 14). 



Enchytraeus monochaetus, Michaelsen, 1888, p. 66, fig. 6 a-c. 



St. 159. 21. i. 27. 53° 52' 30" S, 36° 08' 00" W; depth of net 160 m. Net DLH (large dredge, 

 heavy pattern). About a dozen small worms or fragments of worms, mostly bent or twisted. 



The species was described by Michaelsen as long ago as 1888 from specimens taken 

 in South Georgia. Identification is easy, by means of the setae. These conform entirely 

 to Michaelsen's description — a single seta only per bundle, the 

 ventral setae beginning in segment v, the lateral in xvii or there- 

 abouts ; I find a slight distal curve in some (lumbricilline setae). 

 The spermathecae (Fig. 14) show a broadly pear-shaped ampulla 

 with patent communication, somewhat drawn out, with the oeso- 

 phagus ; the duct is sharply separate, as long as the ampulla. 



Owing to the internal degeneration in the genital segments 

 and the generally unfavourable condition of the worms, I am 

 unable to describe completely the penial body, concerning which 

 Michaelsen has not given us any information. The vas deferens 

 appears to pass backwards in numerous windings for several 

 segments, I think as far as segment xiv ; the penial body seems to 

 have possessed a muscular capsule, and not to have consisted of 

 discrete masses of gland cells after the manner of E. albidus. 



The locality of the specimens deserves a word of note ; they 

 were dredged from 160 m. — a very unusual depth for Oligo- 

 chaetes, which are usually confined to the shore and seldom 

 stray out to sea. Michaelsen's specimens were found with 

 Marionina georgiana about low-water mark, in shaly detritus, 

 among the roots of seaweeds, and in the canal system of sponges. Another species of 

 the genus, M. macrochaeta (Bay of Naples, coast of Ireland), lives, like the specimens 

 of the present collection, below low-water mark. 



Genus Achaeta, Vejd. 



St. MS 71. 9. iii. 26. From moss between Grytviken and Maiviken, East Cumberland Bay, 

 South Georgia. A single specimen ; along with Marionina georgiana. 



The interior of the single specimen was much disorganized, and specific determina- 

 tion was impossible. 



The genus is known from Europe and New Zealand, but not hitherto from more 

 southerly regions. 



Fig. 14. Michaelsena 

 monochaeta ; spermatheca. 

 a. ampulla; c. communi- 

 cation with oesophagus ; 

 d. duct. 



