June, 1917] Hungerford: Life History of a Boatman. 121 



Petric K. — Since this series represents the second lot and was 

 started some two weeks later than those of lot one, a large petrie 

 similar to petrie F, was used as general check on the isolation rear- 

 ings. The eggs were laid on a leaf, during the night of April 11. 

 By April 16 the red eye spots had appeared on several, and at least 

 a dozen had hatched by April 19. The remainder of the eggs showed 

 red eye spots. All had hatched by April 20, and the petrie was 

 swarming with young corixids. Many were removed to make room 

 for the number permitted to remain — still a goodly number. April 

 25 marked the first one to come forth into the second instar. It was 

 milky white with red eyes, and the large glands beneath the dorsal 

 wall of the abdomen showed plainly. The tracheae were to be seen 

 as silver threads branching through the body. April 27 records 

 many second instar forms and on ]\Iay 2, third instar forms began 

 to appear, so that all were in this stage by May 4. On May 7 ap- 

 proximately half of the nymphs were fourth instars, and now meas- 

 uring in length about the diameter of the field of the binocular being 

 used. (Zeiss, 2x eyepiece, 3 A objective.) 



The first fifth instar form came May 13, followed by two more 

 the next day, and all of the rest by May 16. Two adults appeared 

 on May 24, and others followed during the next two days. They 

 were confined here to obtain the time required for coming to matur- 

 ity, but they died, one by one, till the last one departed June 25, after 

 having lived in the petrie as an adult at least a month. It proved to 

 be a male. For this lot, from eggs laid April 11, adults appeared 

 during the period from May 24 to May 26, allowing 43 to 45 days for 

 their development, a time somewhat shorter than those recorded in 

 petrie F. 



Conclusion. 



The notes above presented record the first rearing of the boatmen 

 in close quarters. Rearing may be carried on in petril dishes if given 

 daily attention. In large aquaria, prepared before hand and allowed 

 to reach a natural condition of balance the five or six species with 

 which the writer has had experience may be followed through their 

 life cycles with slight attention. 



In nature the majority of the Boatmen spend their time on the 

 bottom of the shallower parts of the ponds and pools. Foraging midst 



