Oll tlie Inrval dovelopment of Amia calva. 643 



now UDder liis swarmiug cliarges, watcliful apparcntly tliat the 

 stragglers shall be kept up to the rest; aiid in their turn the young 

 fishes seem to fully realize that it is their duty to keep as close as 

 possible to the guardian. It was found by the writer by no means 

 easy to approach the male fish without attracting his notice; he 

 appears to be constantly watchful, and when alarmed exhibits the 

 greatest solicitude for his charges ; sometimes he backs quietly into 

 some reed-screened pool, hiding below in the shadow of floating 

 weeds, his presence betrayed only by the black mass of larvae about 

 him ; at other times he will skulk cautiously away, drawing the swarm 

 after him as rapidly as possible. His duty is clearly to care for 

 his charges, and in the majority of cases when he finds that it is 

 impossible to carry them off with him he will remain quietly and 

 face the enemy. In one instance he was actually pushed away. There 

 can be no question, the writer believes, that the feeling of alarm of 

 the guardian may be transmitted to the young; for in case of need 

 the swarm may be moved more rapidly, the young, excited in their 

 movements, appearing to draw more closely together: under all cir- 

 cumstances they appeared to be careful not to disperse. When the 

 male has been driven away the swarm sometimes becomes so dense 

 that it may be taken almost to a fish by a Single dip of a scap-net; 

 if not interfered with it will gradually move away and take refuge 

 among the floating weeds, often so perfectly that no traces of it can 

 be noticed. Exactly to what period the larval Ämia remains in Com- 

 pany with the male fish has not seen determined exactly. The 

 smallest which in any case the writer has observed measured ^/^ inches 

 (slightly younger than that of PI. 10, Fig. 20), the largest 1 inch 

 (PI. 11, Fig. 25); and as these notes have been made from a large 

 series of swarms, during a period of about two weeks, there is 

 ground for believing that the time of the guardian's care of the move- 

 ments of the young extends from — at least — the stage of the ex- 

 haustion of their yolk supply to that when the caudal fin and 

 scales have attained the adult outlines; — a time certainly not 

 less than four weeks ^). The rate of growth of larvae of the same 



1) The writer has recently learned from his friend Mr. F. B. Sumnek 

 that the period of the attendance of the male is much longer than at 

 first supposed. In Minnesota Mr. Sumnee, records the taking of a 

 swarm of Ämia larvae of which the individuals measured 3 — 4 inches 

 in length, and must have been about four months old; a remarkable 

 fact in connection with them was that all of these young fishes 



42* 



