CATACLYSTA LEMNATA. 77 



feeding well, and by the 5th of May their cases were 

 enlarged with additions from the fresh weed. 



On the 10th of May I saw, with some anxiety, a 

 larva out of its case, apparently dead at the bottom of 

 the water; when taken out for examination it proved 

 to be still alive, but in hopeless plight, infested with 

 extremely minute, slender, whitish, semi-translucent, 

 parasitic worms, whicb, on emerging, coiled and 

 wriggled round their dying victim. Three other larvae 

 succumbed to these parasites soon afterwards. 



On turning over one of the two remaining cases on 

 the 12th of May I was surprised to see the larva 

 walk immediately out of it as though in alarm, and 

 after crawling over the duckweed on the surface of 

 the water partly ascend the side of the glass ; it 

 seemed to be full-grown, so I placed it in a shallow 

 saucer of water, and secured a couple of figures and 

 the following description : 



Length just five-eighths of an inch, or a little more 

 when stretched out to the utmost, in which position 

 it appeared nearly uniform in size throughout, but its 

 more usual appearance while at rest or crawling was 

 to be thickest in the middle of the body, the first five 

 segments tapering towards the head, which is partly 

 retractile into the second segment ; the second seg- 

 ment is longer than the usual proportion, while 

 the third and fourth are shorter than the others ; the 

 thickest segments are the sixth to the tenth ; from the 

 latter the figure tapers again to the thirteenth, which 

 is the smallest segment ; its former knob is not present ; 

 the divisions and subdivisions are all deeply defined ; 

 the anal tip is rounded and but little sloped ; the 

 anterior legs are very well developed ; the ventral ones 

 are full and fleshy, but with small feet ; the anal pair 

 are rather small; the back, viewed sideways, is a little 

 arched, sloping off towards the head, and more to the 

 anal extremity. 



The colour of the head is pale olive-brown, darkest 

 at the mouth, and shining ; the very lustrous black 



