232 ME.. F. E. BEDDABD ON NEW EARTHWOEMS. [Mar. 19, 



this part of the world. It appears to be a very southern 

 Patagonian form. It occurs in fresh water as well as upon dry- 

 land, as is also the case with Acanihodrilus pictus and a few other 

 worms. 



The species is long and slender, and is quite bleached by the 

 alcohol. 



A typically sized specimen selected for measurement was 85 mm. 

 long by 3 mm. broad, and consisted of 92 segments. 



The prostomium is continued for some way over the buccal 

 segment by grooves, but these do not reach the end of that 

 segment. 



The setae are more paired veutrally than laterally, the distance 

 between any two lateral setse being about twice that between the 

 ventral setae. The clitellum occupies segments xiii.-xvi. and is 

 quite complete. 



The nephridiopores open in front of seta 3. 



The oviducal pores lie exactly in line with seta 1. 



The most characteristic external feature in the organization of 

 this worm is afforded by the male pores. These pores in the 

 present genus are, as a rule, very conspicuous, but are more 

 or less rounded orifices confined to the xviith segment. In 

 Microscolex michaelseni the male apertures are represented by 

 crescentic slits, which commence upon about the middle of the 

 xviith segment and extend back to at least the posterior extremity 

 of that segment, and sometimes even encroach upon the xviiith 

 segment. This groove is wider in front than behind. An investi- 

 gation of it by means of transverse sections showed that the 

 spermiducal glands and the penial setae opened in common at the 

 anterior end of the groove where it is widest. The sperm-ducts 

 open at the posterior end. In this wide separation between the 

 external apertures of the sperm-ducts and the spermiducal glands, 

 the present species resembles Microscolex {Wiododrilus) minutus. 

 It will be observed also that the present species is almost an 

 Acanthodrilid in the relations between these organs. The only 

 actual difierence between the Acanthodrilidse and the Cryptodrilidae 

 which is invariable, is that in the one (Acanthodrilidae) the sperm- 

 ducts open a segment behind or in front of the spermiducal glands ; 

 in the Cryptodrilidae, on the other hand, if the two apertures are 

 separated, they are upon the same segment. In Microscolex 

 michaelseni, however, in some specimens at any rate, the apertures 

 must be at least only just not upon consecutive segments, and in 

 other specimens the groove extended well into segment xviii. 

 On segments xvii., xviii. are a pair of rounded papUlae which 

 lie just behind the furrows, separating these segments from the 

 one in front. Sometimes the anterior pair are closer together than 

 the posterior. 



The alimentary canal is not provided with a well-developed 

 gizzard ; there is a rudimentary one only in segments vi., vii. The 

 oesophagus gradually passes into the intestine, which acquires its 

 full calibre in the xvitb. The last pair of hearts are, as is usual 



