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New Species of Stickleback. 



nest about the size of a musket-bullet, constructed of green algse 7 

 and placed in a tuft of submerged grass or aquatic weeds. My 

 eldest boy, who first showed me the nest, assures me that one of 

 the parents, probably the male, as in the case of a common Bri- 

 tish species, remains near the precious deposit, and drives away 

 all intruders. The ova are translucent and colourless, and of the 

 size of a pin-head. They soon exhibit to a close inspection with 

 Ihe naked eye or a magnify ing-gl ass of moderate power, two black 

 specks, the rudiments of the eyes of the future fish ; and under 

 the microscope present the appearance represented in figure 2, 



■f 



o 



Fig. 2. — Egg of G. gymnetes (magnified), 



the embryo being coiled up in the usual manner around the yolk- 

 bag, and occasionally moving by convulsive jerks. At this stage 

 I observed that microscopic animalcules had obtained access to 

 the interior of several of the eggs, and evidently occasioned annoy- 

 ance to the embryo. I have reason to believe that several em- 

 bryos were destroyed in this way, and perhaps the carefully-built 

 nest may have for one of its objects to guard against such attacks. 

 In two or three weeks the young extricate themselves from the 

 Qgg — still only about a tenth of an inch in length, and having the 

 yolk bag attached to the abdomen, as represented in figure 3. 



Fig. 3.— Embryo of G. gymnetes (magnified). 



They swim quickly, and are nearly as dexterous as the adults in 

 avoiding danger and availing themselves of places of concealment. 

 They are now very beautiful objects for microscopic investigation. 

 The head appears a rounded mass of cells. The eyes, however, 

 are well developed, and can be rotated as perfectly as in the adult. 



