REIGHARD ON BREEDING HABITS OF THE DOG-FISH. 135 



dictating the males as the architects. Dean and Ayers (as quoted by 

 Whitman and Eycleshymer) believe the nests to be made at the spawn- 

 ing time or jnst before, by the circling of the fish. 



I have collected two sorts of evidence bearing on this point. First. 

 By stretching a fyke net across the mouth of the bay in which the nests 

 are made, sometime in advance of spawning, I have been able to deter- 

 mine how many and what fish seek the spawning ground first. During 

 ?,even days (April 14th to 20th) forty-four fish were taken, of which 

 thirty-nine were males. In the thirteen nests which were observed to be 

 built in advance of spawning, eleven were seen to be occupied by male 

 fish and no females were seen about them until the eggs were laid. The 

 males had evidently built the nests and were awaiting the females. In 

 eight cases the females arrived and eggs were laid in the nests. Ad- 

 ditional evidence on this point is given under the next head. 



3. What is the method of making the nests f 



I have examined no less than a hundred nests to see whether there 

 was any evidence of this being produced \by a circling of the fish at 

 the time of spawning, but have never detected any such evidence. The 

 surrounding plants are not pressed aside nor arranged in any way like 

 the materials of a bird's nest. The nests have the appearance of having 

 been formed merely by the removal of the water-plants or other mater- 

 ials so as to form a concavity, the bottom of which is formed usually 

 of fibrous roots. 



The nests are frequently under logs or stumps where a circling of the 

 fish would be difficult of execution. 



Besides this negative evidence, we have several times, while sitting 

 quietly watching, seen the swirl of a fish's tail among the water-plants 

 at the surface and have been able to determine that the fish was a male. 

 The fish was in such cases working at the bottom with his head, 

 and freshly cut young shoots of water-plants were often seen floating over 

 such places. In several cases I was able to follow the history of such 

 places continuously and to make out that they were afterward occupied 

 by nests. The male then appears to make the nest by biting and tear- 

 ing away the aquatic plants. 



4. How near are the nests together ? 



This depends on the nature of the bottom. Where the locality is 

 favorable, as about a fallen log, nests may be built within a few feet of 

 one another. With a wide area of bottom suitable for nest building 

 at all points nests are more scattered. I found the average distance of 

 twenty-one nests to be thirty-five feet. Dean says that "as many as half 

 a dozen nests were found to occur within the space of a few square 

 yards." Whitman and Eycleshymer remark, "this needs confirmation." 

 They have found the nests, "never more than four or five in a single bay 

 and usually rods apart." Both statements may be true, the frequency of 

 nests depending mainly on the area of suitable bottom as compared to 

 the number of spawning fish. 



