248 RITTER AND CROCKER 



The reef near the anchorage off the Indian village of Ya- 

 kutat, a large area of which is exposed at extreme low tide, 

 was everywhere strewn with large specimens, and on the Lam- 

 inaria, which grows here in great luxuriance, were thousands 

 of young ones of all sizes, from a few millimeters in diameter 

 to practically the full grown state. Observing that the smallest 

 had only six or eight rays, it occurred to me that the study of a 

 com,'plete series of growing animals would probably reveal a 

 law of their multiplication and might possibly also throw light 

 on the important and difficult problem of the axial relations of 

 the adult star to the larva ; a problem in which I was deeply 

 interested from my interest in the question of the relationship 

 between the Echinodermata and the Enteropneusta. 



I consequently collected and preserved a large number of 

 specimens, the results of the study of which are recorded in 

 the following pages. W F "R 



LACK OF KNOW^LEDGE REGARDING PRODUCTION OF ACCESSORY 

 RAYS IN MULTIRADIATE STAR-FISHES. 



Not much is known about the multiplication of rays in the 

 many-rayed star-fishes. Not only the embryology, but even the 

 early post-larval life of so well known a species as Asterias ten- 

 uis^ina are, according to Ludwig, '97,^ wholly unknown. Here, 

 in a group of approximately one-half the entire number, the 

 rays are, in many specimens, considerably smaller than those 

 of the other half. Whether this is ever due to the addition of new 

 rays during^ a portion of the early adult life does not seem to 

 be positively known. It is certain, however, from the observa- 

 tions of a number of zoologists, Ludwig in particular, that in 

 some cases at least, this disparity in size is due to the regener- 

 ation of the halves of automatically bisected animals. 



It appears to be the belief of most students of asterids that in 

 general the multi-rayed forms begin adult life with the full 

 complement of rays. Thus Terrier, 93, states positivel}^ that 

 in all species excepting Labidiastcr radiosiis the number of 

 rays " est constant a partir de la pe^riode embryonaire " (p. 781). 



1 See Bibliography, p. 269. 



