58 ILLINOIS BIOLOGICAL MONOGRAPHS [178 



cribes to some extent the egg-laying habits of several species. Other work- 

 ers have made smaller contributions to the knowledge of that subject, but 

 have usually assumed that the observations obtained on the particular 

 species at hand must hold true for all members of the group. Since in most 

 cases also the identifications of the material at hand were obviously 

 erroneous, such reports have done little more than add to the confusion 

 that exists. One of the most recent of such reports is that of Wesenberg- 

 Lund (1910). Some of its errors have already been pointed out by Miihl- 

 dorf. This writer, however, does not himself distinguish clearly between 

 the habits of the different species under his observation. From my own 

 observations it is clear that Wesenberg-Lund observed two different 

 species, that he described the egg strings of one species, which he did not 

 identify, and based his conclusions in regard to the protection of the eggs 

 on what he observed in another species, which he identified as Gordtus 

 aquaticus. 



Of the first species he obtained a single specimen with a long string of 

 eggs wound around the stem of a plant. The male is absent and from the 

 illustration given it is evident that the female has no protective instinct, 

 as the eggs are uncovered and partly deserted by the female. From the 

 character of the egg string and the habits of the specimen it is evident that 

 the latter belonged to Chordodes, Parachordodes, or Paragordius. 



In the case of the second species several masses were observed, but the 

 egg strings were not described. Both males and females were present in the 

 mass that was examined and pieces of egg strings were found when the 

 mass was separated later in the season. Had Wesenberg-Lund separated a 

 mass earlier in the season he would also have found nothing but pieces of 

 egg strings. These specimens belonged to Gordius aquaticus or a closely 

 related species which never lay long strings of eggs. 



In regard to the supposed protective instinct of the parent Gordiacea 

 my observations confirm those of Villot and Miihldorf, who were unable 

 to find any evident attempt on the part of the parents to protect their eggs. 

 In nature the specimens of Gordius robustus usually remain with their eggs 

 as in the case of the specimens observed by Wesenberg-Lund. In captivity 

 this species seldom lays eggs and if it does it pays no attention to them, but 

 allows them to drop to the bottom of the aquarium in small fragments. 

 When disturbed in nature it does not hesitate to abandon the eggs. It 

 remains with the eggs not because it tries to protect them, but merely 

 because there is no stimulus to cause it to move on. In case of Paragordius 

 varius the male does not remain with the female even when undisturbed 

 in nature. The female usually remains with the eggs, but I have also found 

 cases in which the eggs were deserted. Even when the female remains 

 with the eggs it usually does not surround them, but merely remains in the 

 same vicinity because it has become sluggish. This type of behavior is 



