252 H. P. KJERSKOG AGERBORG. 



4. In this, it seems to be partly governed by its sense to the 

 pressure of minimum depths. 



5. Three prime causes effect its migratory habits, to wit: 

 (i) sensitivity to light of a certain intensity; (2) search for food; 

 and (3) the breeding impulse. During the breeding season it is 

 neither negative nor positive heliotropic; for it moves up from 

 deeper water to shallower water independently of the directions 

 of the rays of light. After spawning, however, it seems to be 

 positive heliotropic. 



6. It is omnivorous; it is carnivorous. It feeds mainly on 

 Gasteropoda, but also on Pelecypoda, other species of starfish, 

 sea-urchins, crabs, sponges, kelps and algse. 



7. The female seems to have reached a more definite number 

 of rays before maturity, than has the male (see Fig. 4). 



8. Maturity is not entirely dependent on the size of the animal ; 

 i.e., the diameter varies : In immature up to 12 inches; in males 

 from IO 16^ inches; in females from 10^-20 inches. The females 

 are on the average larger than are the males. 



BIBLIOGRAPHY. 



1. Arnold, Augusta Foote 



'13 The Sea-Beach at Ebb-Tide. The Century Co., New York. 



2. Coe, Dr. W. R. 



'12 Echinoderms of Connecticut, Hartford. Bulletin No. 19, Connecticut 

 Geological and Natural History Survey. 



3. '06 Behavior of Lower Organisms. The Columbia University Press, New 



York. 



4. Jennings, H. S. 



'07 Behavior of the Starfish Asterias Forreri de Loriol. Univ. Cal. Pub- 

 lications in Zoology, Vol. 4, No. 2, pp. 53-185. 



5. Loeb, Dr. Jacques 



'03 Comparative Physiology of the Brain and Comparative Psychology. 

 G. P. Putnam's Sons, New York; John Murray, London. 



6. '15 Studies in General Physiology. The Decennial Publications of the 



Univ. of Chicago, Second Series, Vol. XV., Part I. 



7. Ludwig, Dr. Hubert 



'99 Dr. Hi G. Bronn's Klassen und Ordnungen des Thier-Reiches, II. Buch, 

 Die Seesterne. C. F. Winter'sche Velagshandlung, Leipzig. 



8. MacBride, E. W. 



'09 Echinodermata. The Cambridge Natural History. Vol. I., Mac- 

 millan and Co., London. 



9. Ritter, Wm. E. and Gulielma R. Crocker 



'oo Multiplication of Rays and Bilateral Symmetry in the 20-Rayed 

 Starfish Pycnopodia Helienthoides (Stimpson). Proceedings of the 

 Washington Academy of Sciences, Vol. II., pp. 247-274. 



