1912. Friend. — Irish Oligochaeis. 173 



only known for Nottinghamshire (Friend, in Annual Report Nottingham 

 Nat. Society for 1910 — tt, p. 41). 



I come lastly to the description of a curious and in- 

 teresting annelid belonging to a genus which is destitute 

 of setae, and is altogether of unique value to the system- 

 atist. The creatures which are always true to type 

 present no such problems, and afford no similar assistance 

 to the study of evolutionary processes, as do those which 

 may be called abnormal, and the genus Achaeta may be re- 

 garded as a type of the abnormal inasmuch as it not only 

 possesses no setae, but in some instances is also wanting in 

 those transitional vestiges which are spoken of as setae sacs. 



As little is known about Achaeta it may be well if we 

 devote a few lines to a historical survey of the genus. It 

 was founded by Vejdovsky in 1877, the type being Achaeta 

 Eisenii. The chief characters are the absence of setae, 

 the presence in some species of pear-shaped sacs, the 

 absence of dorsal pores ; dorsal unpaired sahvary glands, 

 colourless blood, the dorsal vessel arising in front of the 

 girdle, brain convex behind, and spermathecae free from 

 attachment with the intestine. 



In 1879 Vejdovsky added a second species [A. hohemica), 

 in 1899 Cognetti recorded a third {A. Cameranoi). There 

 the matter stood in 1900 when " DasTierreich — Oligochaeta" 

 by Michaelsen was published. . In 1902 Bretscher added a 

 further species {A. Vejdovskyi), but up till that point, 

 and for five years longer, nothing was known of the Achaetas 

 in England, Ireland, Scotland or Wales. To Southern we 

 are indebted for our first introduction to the genus here. 

 He added a new species (A. minima) in 1907 (Irish Naturalist, 

 vol. xvi. p. yj), and two years later (P. R.I. A., vol. xxvii., 

 p. 165) reported Achaeta Eiseni Vejd. for Ireland, and 

 Achaeta hohemica Vejd. for Ireland and the Isle of Man. 



In 191 1 I found Achaeta Cameranoi Cognetti near Ashby- 

 de-la-Zouch and Achaeta hohemica Vejd. in Kew Gardens 

 and by the side of the canal in the City of Nottingham 

 {Report Nott. Nat. Socy, 1910-11, p. 38), and that is as 

 far as our indigenous records go to the end of 191 1. The 

 earth from Poyntzpass, however, contained one adult and 

 perfect specimen of Achaeta which differs from each and 



