1897.] Friejnd, — Field Days in Ulster, 63 



that at Castlebellingham, Bray, Cork, Kerry, and elsewhere, 

 many new captures may be expected. 



I must guard the collector against one or two possible sources 

 of error. In the first place it must not be supposed that all 

 the water-worms are red, brightly coloured, or easily detected. 

 White worms abound in many places, and in fact the colour 

 varies immensely ; and in the next place let it not be supposed 

 that no worms exist if they cannot be detected with the eye 

 or even with a lens. I shall have to describe specimens taken 

 at different places, the very existence of which I did not suspect 

 until I had my material under the microscope. 



On examining my Belfast specimens I found many things 

 of interest ; respecting which, one or two notes must for the 

 present suffice. 



Heterochaeta costata, Clap. 

 This interesting creature was found somewhat sparingly among the 

 seaweed. As it has been fully described by others I shall only give my 

 own observations, that the results may be compared or contrasted with 

 those of others.! The worm is from half to three quarters of an inch in 

 length, and of a greenish brown hue. It is remarkable for its fan-shaped 

 setae, which occur on segments v. to xii. or xiii. In the hinder segments 

 about one forked seta in each bundle. I found as many as 70 segments 

 in one worm ; the body transparent, oesophagus with chloragogen cells, 

 beginning in segment vi. A pair of enlarged vessels or hearts in viii. The 

 amount of constriction and annulation varies. The system of blood 

 vessels in segments i. to viii. is worthy of careful study. The 

 large ventral vessel in front of segment viii. gives off a complex net- work 

 in each segment. A diagram is necessary to make the matter clear. 



Unclnais Ilttoralls (O.F.M.) 



I find the following notes in my records : — 



So delicate that it fell to pieces when being examined. Could see no 

 uephridia or other organs to answer thereto. Brain seen extending back 

 to segment iiL A small worm i to f inch long, very pale, but with red 

 blood and enlargedheart in viiith. setigerous segment. No eyespots seen ; 

 dark-celled intestine commencing in segment iv. Its motion in water 

 very jerky and peculiar. Tendency to fission behind segment xv. of 

 one specimen. Prostomium with delicate cilia. Four sets of setae in 

 each of the hinder segments, but two sets or bundles only in first three 

 or four. Very liable to attacks from a parasite which fixes itself in glands 

 of the setae. Hence the worm often appears to have a large number of 

 capillary or hair-like setae. This is an ingenious device, and shows how 

 low in the scale of life mimicry operates.' 



* See Beddard, Monograph of Oligochaeta, pp. 257-8 ; Benham, Q.J. M.S., 

 xxxiii., p. 107 seq. ; Claperede, Beobacht. iiber Anat. 1863, p. 25. 

 ' For reff. see Beddard, op. cit, pp. 395-6. 



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