16 and 20 mm in standard length, were collected, but 

 by June 18 and thereafter ju\eniles were fairly numer- 

 ous and exhibiting growth. Hatching time thus appears 

 to be in late May and early June at this latitude. 



It was not possible to rear any fry in the laboratory; 

 thus, all observations on growth of young were made 

 on specimens collected from the study area. At about 

 7 days of age the young fry had attained many of the 

 adult features. Body proportions were essentially those 

 of adults; eyes, mouth, and, presumably, the digestive 

 tract were fully developed, and fins were present. Squa- 

 mation was \ariable, the smaller specimens having fewer 

 scales. In our smallest ( 14 mm in standard lengtii, 

 not depicted) scales had developed on the sides but 

 not on the belly, back, or opercles. The sensory canals 

 of the head were forming, but the opercular spine had 

 not appeared. Pigmentation features were [iresent. 

 though not as discrete and prominent as in adults, and 

 the dark "teardrop" under the eye was still lackiny. 

 The three caudal spots were distinct. 







"■'^iS^^iia.. 





Fig. 6. — Hatchling 2.8 mm in total length, approximately 

 4 hours old. 



Inasmuch as the average si/e of a 1 -year-old E. gra- 

 cile is 30 mm in standard lengtii, the young fish had 

 attained almost iialf of their 1st year's growth in about 

 1 week. 



^^m 



Fig. 7. — Development of squamation, lateral-line system, and 

 sensory pores of Etheoitoma gracite. as illustrated by juveniles 

 of 17. 20. and 25 mm in standard length. 



4 »rs (3) 



3 yrs (40) 



2 yrs (61) 

 I yr (4) 



I 



Fig. 8. — Growth of Etheo- 

 itoma gracile in millimeters 

 standard length (except for 

 hatrhling. whose total lengtii 

 is shown). In each case the 

 horizontal line represents 

 range; the vertical line, 

 mean; the hollow rectangle, 

 one standard deviation to 

 cither side of the mean; and 

 the Mack rectangle, two 

 standard errors to either side 

 of the mean. Numbers in 

 parentheses arc specimens 

 measured. 



I HATCHLING (I) 



2 wks (6) 



Iwh (2) 



2 3 



15 



20 



25 30 



MILLIMETERS 



^•> 



40 



45 



I 



