SOME EAST SUSSEX OLIQOCHMTS. 83 



very rich in material, and both here and in the runnels which 

 lead to it I have found material which has not up till the present 

 Occurred in any other locality. One or two of the species merit 

 special notice. 



Ilyodrilus meganymphus, Friend (1912, J. K. M. S., p. 289) ; 

 the locality unfortunately not then recorded), belongs to the 

 Tubificids. Its specific name is due to the large spherical 

 coelomic corpuscles (nymphus = lymphus, whence our term 

 lymphatic). In this respect the creature resembles Rhyacodrilus, 

 which is a link between the Tubificidce and the Naididce (4). 

 The chloragogen cells begin in segment 4, which is in advance 

 of the usual position. Curiously enough, while it simulates 

 Rhyacodrilus in the matter of coelomic corpuscles, it closely 

 resembles the red-blooded Enchytrseids in the vascular system. 

 This is of peculiar interest, seeing that the blood-vessels in the 

 Tubificidce are usually much more profuse and the system much 

 more complex than is the case with the Enchytrseids. It is the 

 discovery of such unusual forms as these which at once makes 

 systematic lists and definitions a problem, and yet throws such 

 a flood of light on the evolution of species. 



Haplotaxis gordioides (G. L. H.). In 1896 I gave an account (5) 

 of a worm which had been sent to me by a medical man in 

 Essex. It was new to science, and was named Dichceta curvi- 

 setosa, Friend. The name was changed in 1899 to Phreoryctes 

 dichcetus, Friend. Up till the present no further specimens have 

 been found. Michaelsen (10) in 1899 published an account of 

 P. gordioides, and included the Essex species, in spite of the 

 great differences between it and the type. In 1900 (9) he issued 

 his valuable monograph on Oligochsets, and called the worm 

 Haplotaxis gordioides, and still persisted in including the Essex 

 form. On December 21st, 1911, I had the good fortune to find 

 the worm which bears this name in Alexandra Park, Hastings, 

 and was able instantly to recognize it and to see how greatly it 

 differs from P. dichcetus. Thus, at the present time we have two 

 species of Haplotaxidce in England ; in addition to a third well 

 worm found in East Anglia but not yet described. 



Tubifex heuscheri, IJret., was also collected near the park. It 

 has not been found elsewhere in Great Britain up till the present 

 time ; making the third unique species. 



h 2 



