2 BULLETIN OF THE 



Before we can arrive at any trustworthy conclusions as to the mor- 

 phology of the Echinoderms, animals as varied in external form as the 

 Crinoids and Holothurians, it is necessary for us to know the character 

 of the early diiferences in the calcareous plates, and their sequence and 

 mode of growth in the different groups. These plates are the struc- 

 tures which, more than any others, give the variety in external form to 

 the different members of the Echinodermata. It may be confidently 

 said that we know the general outlines of the growth of the primary 

 plates of a representative Comatulid, Ophiuran, and Holothurian. We 

 know next to nothing of the early formed plates of the Echinoids, 

 and there is no subject which offers more interesting possibilities of 

 discovery than this. Little is known of the mode of growth of certain 

 of the plates of the body and arms in those Asterids which have a 

 nomadic brachiolaria.* 



The following paper, therefore, is offered as a contribution to the 

 recorded observations on the growth of the plates in the starfish. 



The common species of Asterias found at Newport l'esembles closely 

 Asteracanthion berylinus of A. Agassiz, and has close affinities with 

 Asterias vulgaris, SI., and A. Forbesii, Desor.f Although I suppose it 

 to be the same as berylinus, there are some peculiarities of coloration % 

 which would lead one to regard them as different. "While the species 

 of starfishes found by me at Newport, in the adult condition, have fea- 

 tures of both A. vulgaris and A. Forbesii, it is not possible for me to 



* Our knowledge of the growth of the plates which form the mouth parts of 

 the starfish is fragmentary and unsatisfactory. 



t The genus Leptasterias is thought to be sufficiently well separated from 

 Asterias by the character of its development to merit a new name, as shown by 

 Prof. Verrill. 



t The fact that all females of both Asteracanthion pallidus, Agass., and Astera- 

 canthion berylinus, Agass., have a bluish tint, while the males have a reddish 

 color, according to A. Agassiz, indicates that there is a difference in color in the 

 female starfishes which we studied. The color of the females of the species of 

 starfish which I tried to fertilize was different from those of the species of Astera- 

 canthion used by A. Agassiz in the artificial impregnation of the starfish. Many 

 specimens of female starfishes, which had ripe ova, have a chocolate-brown color, 

 and a bright orange madreporic body. Starfishes of this color were the only 

 ones which cast their eggs, although I had in the aquaria bright red and bluish 

 colored starfishes of all sizes. In A. Agassiz's specimens those with a bluish tint 

 are invariably females, while the reddish brown or reddish are males. I do not 

 know the color of our male Newport Asterias, but several specimens of the reddish 

 brown specimens laid eggs in great numbers on several occasions. Ova nearly 

 mature were also cut out of specimens of this color. 



