72 COPEIA 



This darter is abundant in some of the foothill 

 streams near Boulder, Colorado. Males in full breed- 

 ing colors, with milt flowing freely when touched, 

 and females with mature ova which could be dis- 

 charged with slight pressure, were found as early as 

 April 22 and as late as June 1, in Dry Creek, a small 

 stream a few miles east of Boulder. These breeding- 

 fish were taken in water from three to four feet deep. 

 The temperature of the water varied from 12 °C. to 

 15° C, and its alkalinity equaled a 1-800 normal solu- 

 tion of Potassium Hydroxid. The darters were espe- 

 cially fond of pools where the bottom of the stream 

 was covered with a heavy slime and masses of rot- 

 ting vegetation, which had to be removed before the 

 fish could be captured. When disturbed, the darters, 

 which could be seen resting on top of this slime, bur- 

 rowed into the soft debris by a series of quick move- 

 ments of the pectortal and ventral fins. This pref- 

 erence for the deep pools at this time seemed to be 

 correlated with the breeding activities of this species, 

 as Etheostoma iowae was found usually under peb- 

 bles in swiftly running water and in shallow riffles 

 during the fall, winter and early spring. 



The incubation period of the eggs of Etheostoma 

 iowae kept in running water at 13oC. to 16oC. in the 

 laboratory, was comparatively short, occupying from 

 18 to 26 days. The germ ring was clearly visible by 

 the twentieth hour after fertilization, and the ma- 

 jority of the eggs of one large series hatched within 

 30 minutes of each other on the twenty-fourth day. 

 The newly-hatched darter was 3.4 millimeters in 



length. _> t» T 



Bertram B. Jaffa, 



Boulder, Colorado. 



THE BREEDING HABITS OF THE VIVI- 

 PARUS PERCH, CYMATOGASTER. 



The family Embiotocidae includes a number of 

 interesting percoid fishes. They have all developed 



