IIO CALIFORNIA ACADEMY OF SCIENCES. [ 3 d Ser., 



peared the surface is almost as rough and hard as that of 

 an adult female. 



It is a noteworthy fact that the gills are not the first struc- 

 tures to show indications of metamorphosis , and that they do 

 not fully disappear until after the process is complete in other 

 respects. 



On this point I quote from my notes: "Oct. 12, 1895, 

 captured at Little Lake Chabot a larva 6 cm. long, tail-fin 

 nearly reduced, dorsal skin almost completely papillated, 

 ventral skin yellow, but gills only slightly reduced. Very 

 little of the longitudinal dorsal stripes remaining — back 

 nearly uniformly brown." 



On October 19 the note made was: "Larval characters 

 all gone except the gills. Specimen has not yet come to 

 the surface of the water." 



On the 23d the gills were found to be greatly reduced; 

 the stubs had become much more highly pigmented than 

 they previously were, so much so that the circulation in 

 them could be but very imperfectly seen. 



The statement in my notes that the larval characters were 

 " all gone " excepting the gills before the animal began to 

 come to the surface of the water, if strictly true for this case 

 would certainly not be so in general, for the usual thing is 

 that they spend considerable time at or near the surface, at 

 least those kept in confinement do, while they yet retain 

 larval characters quite distinctly. 



That some larvae should undergo transformation any way, 

 even though it means destruction to them, while others kept 

 under appreciably the same conditions should for so long a 

 time show no indication of metamorphosis, furnishes a 

 beautiful illustration of the delicacy of balance, but at the 

 same time the intricacy of the forces, which determine the 

 life of an organism. 



It also illustrates well what widely divergent results may 

 come from causes with differences so trifling as to escape 

 recognition without the most careful scrutiny, sometimes 

 even with it. My larva; still living as such and now con- 

 siderably more than a year old have been kept in essentially 



