422 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.xxxii. 



Several facts there published have an important bearing in connec- 

 tion with the present paper. The author writes on page 12: 



My ol)servations commenced in 1896, since when I have had good opportunities 

 of studying its life history, having repeatedly bred then! from the egg to the adult 

 stage, and so on again. 



So far as known this is the only instance on record of the actual 

 breeding of any parasitic copepod throughout its entire life histor3\ 

 The facts presented, therefore, are of special value since the}'^ are 

 actual facts and not partial deductions. 



On pages 19 and 20 are many interesting statements in reference to 

 ovipositionand the time required for hatching. 



Statistics which I have taken from twenty cases of oviposition show that the aver- 

 age time from the laying of the egg until hatching occupies 25 days. 



It was found that temperature greatly influences the length of incu- 

 bation, and that this period also varies still more widely for reasons 

 which are apparently inexplicable. In testimony thereof witness the 

 following: 



In confinement I have records of ova laid on November 29 and hatching on May 

 6 of the following year. On the other hand, some batches laid on August 30 and 

 September 2 remained over the winter and hatched on April 10. 



The former is a period of five months and eight da3^s, the latter of 

 seven months and two days either period being far in excess of any 

 previously recorded. It must be remembered also that these were 

 "in confinement'"' — that is, in aquaria, where the temperature would 

 be much higher than out of doors during these winter months. 



The moral for the investigator would seem to be that if the eggs he 

 is watching do not hatch within the allotted time he must still keep 

 them, even to a period of six months; they may yet come around all 

 right and hatch into normal larvfe at the eleventh hour. 



Again, Clark states that eggs which began hatching on February 27 

 and continued into March "became adult on June 27, and laid ova 

 which hatched on July 20 (twenty-three days.""') In this case the entire 

 period from the birth of the parents to the birth of the children was 

 a week less than five months. 



This enormous difl:'erence from an average of 25 daj^s to a maximum 

 of 212 days emphasizes more forciblj^ than ever before the necessity 

 of keeping an accurate record of the attendant temperatures and con- 

 ditions if we would form a rational conclusion in reference to the 

 period of incubation. Fortunately the daily temperature of the water 

 was carefully recorded during the incubation period of both of the 

 larva; here described, and is supplied in the account as given. It 

 would be very interesting to determine what relation, if any, the 

 length of the incubation period bears to the subsequent length of life 

 of the Argulid. Would the continuance of the larva? for 200 days 

 within the Q^g tend to shorten its subsequent life? 



