106 SCIENCE PROGRESS 



and for many years it was lost to sight. It was rediscovered 

 in 1890, but as the connection was not then recognised 

 Michaelsen named it Allolobophora hermanni. In 1896 de 

 Ribaucourt gave a full description of it as found by him in 

 company with Lumbricus michaelseni in extremely humid soil. 

 He remarks that by its form and manner of life it appears to 

 be a link between the terricolous and the limicolous species. 

 But as yet the connection between the two had not been 

 suspected. Rosa, in 1893, had given Michaelsen's A. hermanni 

 place in his Revisione, but does not allude to Helodrilus, and 

 in 1895 Beddard has the following note: " H. oculatus Hoffm. : 

 This is an extremely mysterious species, neglected by Rosa in 

 his recent revision of the Lumbricidae, and therefore probably 

 not believed by him to be a Lumbricid. Its most remarkable 

 structural peculiarity is a pair of eye-spots on the buccal seg- 

 ment. There are four pairs of setae in each segment, which 

 are straight instead of curved, and said to be black ; the male 

 pores are upon the fifteenth segment. The body is elongate 

 and pink in colour; the length at most 135 mm. It occurs on 

 the seashore in pools more or less dried up." Beddard adds 

 that " Vaillant suggests that this worm is probably a Tubificid, 

 on account of the presence of eye-spots, and because of its 

 habitat. The black setae are very suggestive of what I have 

 myself observed in Tubifex rivulorum. But it does not seem 

 to me that we are justified in relegating the genus to any family 

 at present." 



When, in 1900, Das Tierreich : Oligocholia appeared, Michael- 

 sen put the matter right. He showed that H. oculatus Hoffm. 

 and Allolobophora hermanni were one and the same, and gave 

 Germany, Switzerland, and Italy as its distribution. In the 

 course of time England was added to the list of habitats. As 

 I was exploring the pond in the Cambridge Botanic Garden 

 in July 1907, I found several adult specimens of the worm, and 

 sent an account of it to the Gardeners' Chronicle some time later. 

 Next it was found by Mr. Evans near Edinburgh, and at the 

 same time I found the immature forms at Malvern, with the 

 eye-spots distinctly visible. But though I kept it under obser- 

 vation for two years, I was never able to find an adult. During 

 the past three years I have taken H. oculatus from mud on the 

 banks of the Thames at Kew, near the sea at Hastings, by the 

 dykes in Pevensey Marsh, by streams and ditches in Derbyshire 



