172 The Irish Nahiralisi. September, 



seldom exceed an inch in length, and are frequently only 

 2 — 4 mm. long. They are distinguished from the larvae 

 of flies and other lowly creatures by the number of seg- 

 ments, the presence of setae, the arrangement of the 

 internal organs, and other well-known marks. Occasionally 

 it happens, however, that we meet with a specimen which 

 is wanting in setae (or is achaetous) as in the genus 

 Achaeta, but even here there are well-defined differences 

 between the Enchytraeid and the larvae which at first 

 sight resemble it so nearly. I have to record four species 

 belonging to three separate genera. 



5. Enchytraeus minimus, Bretscher. 



Has of late come to be well-known. It was first described in 1899, 

 but was not recorded for Ireland till 1907 {Irish Naturalist, vol. xvi., 

 p. 72), when Southern placed it among the species found on Lambay, and 

 shewed that Michaelsen was wrong in suggesting its probable identity 

 with E. argenteus Mich. {E. parvulus Friend). To Southern also we owe 

 figures of the brain, nephridium and dorsal vessel. I cannot, however, 

 agree with Southern {Contrih. Monograph of British and Irish Oligocharta, 

 Proc. R.I. A., vol. xxvii., 1909, p. 157) that E. minimus is identical with 

 E. turicensis. In England, in any case, I find marked differences between 

 the two species, and I have given a full account of E. minimus in /. R. 

 Micro. Society, 191 1, pp. 730 — 734, with figures. My reading of the 

 dorsal vessel differs from that of Southern, but it is well-known that all 

 these microscopic creatures are subject to many aberrations. For E. 

 turicensis I may refer to The Naturalist, August, 191 1, p. 293. 



6. Fridericia Mishaelseni, Bretscher. 



Southern [Proc. R.I. A., vol. xxvii., p. 163) has a note on this species to 

 which the student interested in details may be referred. The specimens 

 received from Poyntzpass agreed with the Irish, and Danish specimens in 

 absence of glands at the opening of the sperma thecal duct. During the 

 present year I have found both forms in England, and when the glands 

 are present they form a very striking and unmistakeable character. 



7. Fridericia bisetosa, Levinsen. 



Quite a number of bisetose forms have of late been discovered. When 

 perfectly mature their differences are sufficiently obvious and need oc- 

 casion no difficulty. But when young it is often impossible to be quite 

 certain to which of the allied species the creature is to be referred. During 

 the past year hundreds of specimens have been submitted to examination, 

 and I conclude that we may safely place this species on record for Ireland. 

 It can readily be distinguished alike from F. paroniana Issel, which 

 Southern has already noted (Proc. R.I. A., vol. xxvii., p. 161), F. magna 

 Friend {ih, 165, note), and F. diachaeta Bretscher, which is at present 



