312 E. H. STRICKLAND. 



to find a place of exit. The head was kept constantly moving 

 over the intern, il surface of the abdominal hypodermis and was 

 even sometime- thrust far into the thoracic region. The move- 

 ments appeared to cause the host great pain, especially when the 

 thoracic region was visited. Finally after the entire worm had 

 been several times t\\ isted round in tin- body the head was pressed 

 against the junction of the third and fourth abdominal segments 

 and a hole was quickly made through which the worm slowly 

 emerged. The worm, measuring 3 cm., took in all 27 minutes 

 to disengage itself after puncturing the skin of its host. At first 

 the operation was very slow and the constant writhing and turn- 

 ing of the host impeded rather than aided the movements of the 

 parasite. When about 50 mm. were exposed the head was twisted 

 around the body and the remainder of the worm was more 

 rapidly forced out, finally becoming detached from the host in a 

 tightly knotted mass which soon straightened out. The larva 

 meanwhile rapidly shrank, and in about half an hour was dead. 

 The worm apparently can leave the abdomen at almost any 

 point, though the thin junction between two segments is usually 

 chosen. It is probable that the death of most parasitized larxa- 

 is directly due to the escape of the worm, which in all obser\ ed 

 cases occurred some time before maturity. 



On raising leaves in the bed of a stream a little below a large 

 colony of Sim it! in ni larv;e it was found that they had under 

 them several of these white worms. This year most of the worms 

 had CM -aped by the beginning of May, and ha\e since been lost 

 sight of, though while examining a stone microscopically for a 

 second brood of Sininliiini eggs, on May 29, one or two minute 

 worms were seen, which may have, been young Mt'rniix. Xo 

 Sinniliitm eggs could be observed. At a still later date, August 

 3, a full grown, though dead, Mermis was found under a stone 

 in the bed of the .stream. 



PKK< EN i A.GE OF I. AKY.K l\l I SI I-.D. 



Several leaves co\en-d with larv.r were taken from a stream 

 in Forest Hills for the purpose of determining the percentage of 

 parasitism. 



These larva?, which repiv-eiiied \\\ ( - species Sininliiini hirli/>fs. 



