INTRODUCTION. xlv 



We have frequently observed the young Talitrus escape 

 from the mother, upon the capture of the latter; and 

 from the active state of their existence at this time, they 

 appear as if they had long been capable of so acting, if 

 they had required it. The observation of Dr. Salter on 

 the common Gammarus, detailed at page 380 of the first 

 volume of this work, fully confirm this fact — as does the 

 circumstance that the young of Arctui'us are protected by 

 the mother, who supports and carries them about on the 

 antennae. Also we have been able to corroborate the 

 observation of ]Mr. H. Goodsir, that the Caprella carries 

 about its young attached to its body. These, together 

 with the fact that many genera, particularly of the 

 Podocerida>, protect and nurse their young for some time 

 within nests, which they build apparently for no other 

 purpose, afford abundant proof that in these animals 

 there is a conscious love of ofl'spring that appears to 

 be less marked in animals far higher in the scale of 

 scientific classification. 



When the young of Gammarus first swims about as a 

 free animal, it only resembles the parent in a modified 

 degree. The antennifi show no distinction between the 

 peduncle and the flagellum. The latter is shorter, and 

 consists of but five articuli, while thirty to forty may be 

 present in the parent. This relative proportion is visible 

 also in the lower antennie, and in the secondary appen- 

 dage of the upper, which increases with advancing age, 

 until the adult stage is acquired. 



In the structure of the eye we see the same gradual 

 increase going on after the animal has become free. The 

 lenses in the young are from ten to twelve in number, 

 whereas, in the adult, from sixty to eighty may be counted. 

 In many genera it also changes its colour, as does also 

 that of the animal itself. 



