252 REPORT OF THE COMMISSIONERS OF 



A few rushes which were found floating on the surface were removed before the 

 present photograph was taken. It was a nest of this kind which the writer sketched 

 in an earlier paper on the subject. The present figure shows also the concave nature 

 of the bottom of the nest, and it even indicates the delicate rootlets of the rushes 

 projecting inward. It cannot be stated that the nest of the dogfish is always as 

 elaborately constructed an affair as the present figure indicates.* In the writer's 

 experience, however, he has found that a definitely prepared spawning place occurs in 

 as large a proportion of instances as eight or nine out of ten. Occasionally, when 

 the fish selects its spawning place in deeper water — four feet or more in depth, — the 

 bottom and its adjacent hummocks may be of such a character that the fish can utilize 

 the natural conditions with a minimum of effort. An instance of this kind is shown 

 in Figure 5, where a natural outline for a nest is formed by clumps of rushes. The 

 water is here slightly over a yard in depth. In the case of this nest there were no 

 "supernatant" rushes present. The eggs were exposed to the sunlight and the fish 

 itself was largely exposed. Even at this depth the eggs can be seen clearly a couple 

 of yards away ; there seems to be a peculiar brilliancy to the eggs which causes them 

 to stand out in bold relief against the dull colored background. Perhaps the most 

 characteristic nest shown in the present figures is that of Figure 6. It was photo- 

 graphed just as the boat approached it, and the guardian fish could still be clearly 

 seen. It will be noted that the water surface is encumbered by but few rushes. The 

 open .space serves to let the light into the nest, and is, I believe, of direct value in 

 hastening the development of the eggs. It is in this clear space, by the way, that the 

 fish rises to the surface, from time to time, for respiration. Another very typical nest 

 is that shown in Figure 7. This, too, was photographed at the first approach of the 

 boat, the fish having just been driven away. Here again the central portion of the 

 nest is entirely open; the "supernatant" reeds are practically absent and it is only 

 the slight overbending of the marginal rushes which makes the nest appear at the 

 surface smaller than it really is. To give an idea of the general character of the 

 bottom of such a nest, the writer caused it to be removed. The rootlets which 

 attached it below were clipped away, and a towel was passed beneath it. The bottom 

 of the nest was now lifted out but little injured. It was then placed in a bucket 

 of water and photographed (Figure 8). The present illustration is accordingly of 

 interest as showing the exact character of the bottom of a nest. One observes the 

 dense masses of eggs scattered upon it, and the mossy and matted rootlets which 

 smoothly line it, which suggests the lining of the nest of a bird. Before concluding 

 this section of the present paper the writer may be permitted to quote several para- 



* The fish, as Fiilleborn notes, is "particular" in selecting the site of its spawning place. And 

 favorable nesting places are probably occupied from year to year. 



