494 PARENTAL CARE AMONn FRESH-WATER FISHES. 



There is, in other respects than those inentioned, much more di- 

 versit}' than in most other families, aUhoii^h the species are not very 

 numerous; their exact number, however, is uncertain. The species 

 appear to be subject to unusual variation, and characters which would 

 be of specific importance in most groups in this appear to be merely 

 individual deviations. A result of this Avas that before the extent of 

 this variability was appreciated many specific names Avere based on 

 what later proved to be unstable characters. For instance, an able 

 French naturalist, Prof. P]mile Blanchard, thought that in France 

 alone there Avere seven species Avith three dorsal spines and four 

 species AA'ith many. He was CA^en strongly inclined to think that 

 other species (plusieurs especes) remained to be discovered. 



Naturalists of the present day reduce the seven to one (Oaf^feroft- 

 leii^ acvleatuH) and the four to another {Pi/(/oste>if< or Pnnf/)f'nifi 

 pifi)f/'ifJ>/s). It is not impossible, however (but not probable) that 

 it may be found that from the extreme of undue multiplication or 

 '' si)litting '" of species there has been a i-evulsion to an opposite 

 extreme of excessiA^e " lumping."" INIuch more certain ai'e the genera : 

 these are readily separated and stand out boldly in nature. Three 

 of these occur in the Old World — (Tasferofyteus, Ptm(/^fii/.9 {Pygof<- 

 teui^), and S/miaehm. Gastcrosfens and Pvnc/itivs are equally well 

 represented in North America, and the absence of Spinarliia is more 

 than balanced by the existence here of tAvo unknoAvn to Europe — 

 Evcalia and Apeltes. Of all these the nesting habits are more or 

 less knoAvn. 



All the sticklebacks take care of their eggs and the ncAvly born 

 young, but it is the male, and not the female, that exercises parental 

 care; he it is that builds a nest that Avould do credit to a bird and 

 drives or entices the full female to enter into it and deposit her ripe 

 burden. When a sufficient supply of eggs has been secured, the male 

 closes the nest and remains in charge till the young haA^e reached 

 a size Avhich he considers to be sufficient to enable them to AAander 

 aw^ay and seek their OAvn living. 



The sticklebacks have been divided among three groups or sub- 

 families. 



"A 



Fig. 80.— Ten-spined Stickleback {Fungitiuspungitius). Fig. 81.— Gasterosteus. 



After Storer. Pelvis below. 



The best-knoAYu forms, oi- Gasterosteines^ have the pelvic bones 

 forming an arroAv-like or V-shaped plate below, the point extending 

 backAvard. 



