320 C. D. SOAR on hydrachnil»j:. 



in the water swam about, and appeared to make no attempt to 

 get out. The larva of Hydrodroma always remained in a 

 sluggish, sleepy sort of way at the bottom of the tube. Eylais 

 extendens did not seem to trouble very much, and appeared 

 quite as much at home outside the water as in ; but with JDiplo- 

 dontus despiciens it was quite different. Its first object in life 

 appeared to be to get out of the water and away somewhere 

 else as soon as possible. It was with great difficulty that one 

 was secured under the microscope for drawing, so quick and 

 sudden were its movements. It is in this form that they pro- 

 bably become parasitic on some other forms of pond life. 



My aim this year has been to make myself familiar with the 

 different forms of larvae as far as possible, and next year I 

 hope, by a systematic search among all kinds of pond life 

 that are likely or unlikely to be the hosts of these creatures 

 during this stage, to see if the same species of Hydrachnidce 

 are always parasitic on the same hosts. The drawings of the 

 larva? mentioned are on the table. 



Third stage, the Nymph. — In this stage they attain their full 

 complement of legs, viz., eight, and they are very much like 

 the adults, so much so that in the majority of cases it is quite 

 easy to tell to what species they belong. The genital area and 

 the size constitute the principal difference, the genital suckers 

 being as a rule only two on each side of the fissure. They are 

 free swimming, and are as freely taken in the net as the adults. 

 How long they remain in this stage I cannot say. I took a 

 large quantity in Wales this year of a species of Neswa, and 

 some are still alive. Some specimens of Nescea pulchra (Koch) 

 were also found in the inert stage, which constitutes the change 

 from the Nymph to the Imago. Two specimens only were ob- 

 tained on a piece of pond weed in the Warren at Folkestone, 

 This is the only time I found Hydrachnids in this form, but no 

 doubt all the species go through similar changes. Nymphs of 

 several genera were kept for a long time in confinement, but 

 they never showed the least signs of going into the inert stage, 

 neither were they observed changing their skin. Next season 

 I hope to be able to carry these observations further. 



Fourth stage, the Imago. — This is the adult stage, when these 

 interesting creatures attain all their brilliant colouring. These 

 colours, which in some cases are quite metallic, as for example 



