52 CONNECTICUT GEOL. AND NAT. HIST. SURVEY. [Bull. 



Because of the vastness of the volume of the surrounding sea 

 water it is only when both sexes discharge their products within 

 reasonable proximity to each other and at very nearly the same 

 time that the eggs have any chance of being met by the sperm 

 cells. Nevertheless, under favorable conditions of currents in 

 the water, the sperm cells may be carried to eggs deposited 

 at some considerable distance, probably several hundred feet. 

 Except in rare instances, therefore, such individuals as fail 

 to mature their sexual cells at the normal period and discharge 

 them into the water in the vicinity of one or more individuals 

 of the opposite sex give rise to no offspring during that season. 

 Moreover, it is uncertain as to whether such sexual products 

 as mature at unusual seasons are discharged from the body. 

 The northern starfish, Astcrias vulgaris, exhibits breeding 

 habits similar to those described for the common starfish. In 

 this species also the sexual products mature in summer. 



The breeding habits of the blood starfish (Henricia) differ 

 widely from those of the two preceding species of Asterias, 

 in that there is no free-swimming larval stage. The eggs of 

 this species are large and heavy, being filled with an orange- 

 colored yolk. But few eggs are produced by each female. They 

 give rise to embryos which pass though an abbreviated larval 

 development, and quickly assume the form of the adult. Fisher 

 has recently described* the brooding of the eggs in the case of 

 one of the Pacific coast varieties of this species. The brood pouch 

 is formed by arching the disk and bringing the bases of the rays 

 close together. Into this cavity the eggs are tightly packed, and 

 the developing young are thus protected by the mother until after 

 the adult form has been reached. 



The slender-armed starfish {Asterias tenera) is stated to 

 brood its eggs and developing young in the same manner. 



DEVELOPMENT 



Common Starfish. — The eggs of the common starfish, as 

 stated in the preceding chapter, are set free in the surrounding 

 sea water mainly during the month of June. The developmental 

 processes are very complicated, and many of the details are not 



• U. S. National Museum, Bull. 76, p. 277, 191 *• 



