140 THE GROWTH OF GROUPS 



observed an offspring of vertebrate stock differing from 

 its parents in all parts of its constitution, that is to say 

 having a different specific facies from its parents. We 

 may have to wait long before such an observation is made. 

 In the mean time our attention may be turned to those 

 characters affecting a particular portion of the body, the 

 so-called varietal characters, for we know, without doubt, 

 that offspring and parent may differ from one another 

 in respect to them. Moreover, it is evident that many of 

 our so-called species differ from one another in respect 

 to such characters. 



The following case of a polymorphic species of fish is 

 of interest in this connection, since we can see it in an 

 example of a character which affects the whole outward 

 appearance of the animal to a remarkable extent, and 

 is therefore more like the specific character as conceived 

 by De Vries. 



Malthopsis is a peculiar genus of fish which has been 

 obtained four times in the trawl of the Survey Ship In- 

 vestigator from considerable depths near the Andaman 

 Islands. A single specimen was also obtained by the 

 German research vessel Valdivia off the East African 

 coast. The genus has been recorded from near the 

 Hawaian Islands, but as described and depicted the 

 specimens from this place differ in certain respects from 

 those we are about to consider ; at all events, they are not 

 of the same species. Malthopsis is common locally, but 

 not generally, in the seas round India. Thus it was 

 obtained on four out of twenty-one occasions when the 

 trawl was used near the Andamans in depths greater than 

 a hundred fathoms. The four stations are not very 

 close together, nearly two hundred miles intervene between 



