228 s. GOTO. 



confine my descriptions to those points on which the statements of 

 other writers require either confirmation, correction or extension. 



As the rapidity of development appears to be subject to 

 considerable variation I shall, in the present paper, adopt the 

 notation of MacBride ['96] for the stages of metamorphosis, in 

 which these are repiesented by the first letters of the alphabet. 

 Thus, stages A, B, C, D, E, F and G correspond respectively 

 to those of the 2nd day, 3 days, 6 days, 5 days, 8 days, 9 days, 

 and 10 days of Ludwig, the last stage representing the first 

 completion of the star. In the case of my specimens the same 

 stages extend over a period of 20 days, and thus it seems that 

 their development was half as fast as those of Ludwig. This 

 discrepancy can be conveniently avoided l)y adopting MacBride's 

 notation, which has the further advantage of allowing interme- 

 diate stages to be denoted in the form of a fraction. Thus in 

 the following pages I shall denote the stage intermediate between 

 B and C stage B/C. 



1. External Feature. 



In the first place a few words must be said about the ori- 

 entation of the adult starfish. In Ästerias pallida I have shown 

 that the plane of bilateral symmetry of the adult coincides with 

 that of the larva, and that the oral side of the former is the 

 anterior of the latter and the aboral side the posterior. We 

 must now examine if the same method of orientation can with 

 propriety be applied to Ästerina gibhosa, especially as this species 

 has been studied by more than one eminent investigators and 

 none of them has pointed out such a coincidence of the planes 

 of bilateral symmetry of the larva and adult. I have shown 

 that in Ästerias pallida the remnant of the preoral lobe is, in 



