SHALLOW-WATER STARFISHES I7 



digestion of food and cause more rapid growth and earlier maturity, 

 if not greater reproductive powers. 



It would be a very interesting experiment to try breeding six-rayed 

 or seven-rayed varieties of some common five-rayed species. 



I have found five-rayed young (about 5 per cent) among those 

 carried by a six-rayed mother, in the case of Leptasterias epichlora. 

 Fisher states that he has found seven-rayed young in the gonocodium 

 of an eight-rayed Pteraster obscurus, and one with nine rays. That 

 six-rayed and seven-rayed varieties might be easily obtained by 

 selection and isolation is very probable. I have observed that in the 

 case of our common New England starfish (Asterias forbesi) six- 

 rayed and seven-rayed individuals are much more common in some 

 localities than elsewhere, indicating, perhaps, a tendency to the 

 inheritance of these features. 



SPECIES, SUBSPECIES, AND VARIETIES. 



Within the limits of recognized species, certain groups of indi- 

 viduals, apparently having a definite distribution and more or less 

 permanency of characters, are regarded as bathymetrical or geo- 

 graphic races. Such races are here called subspecies. 



In certain genera, for example Asterias, Henricia, Solaster, speci- 

 mens occur which cannot be referred definitely to any species or sub- 

 species. Some of these appear to be local variations, due to unfavor- 

 able environments ; " sports," " freaks," or " hybrids ; " others may be 

 abnormal individuals. They are here called varieties. If in future 

 the characters of any of these varieties prove fairly constant, it may 

 become necessary to elevate them to subspecific or even specific rank. 

 To determine the status of these forms, much larger series of speci- 

 mens than are at present available will be necessary. 



It is not unreasonable to think that some of these " varieties " and 

 " subspecies " are incipient species, now in the process of evolution, 

 and that eventually some may become fixed species, while others will 

 disappear by the elimination of the most unfit. 



The Northwest Coast appears to be one vast nursery for the origi- 

 nation and evolution of new varieties, subspecies and species of star- 

 fishes and various other groups of marine animals. 



A peculiar difficulty in the determination of genera and species of 

 starfishes consists in the fact that many, especially of the Asteriidae, 

 do not attain their adult characters until of considerable size, so that 

 young, or even half-grown specimens, may appear to belong to a 

 different species, or even a different genus, for the more complex 



