2 BULLETIX OF THE 



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

 phulo^y of the Echiuoderms, animals as varied in external foi'm as the 

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

 of the early ditfcrcnces in the calcareous plates, and tlieir sequence and 

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

 tures which, more than anv others, jrive the variety in external form to 

 the diftei'ent members of the Echinoderniata. It may be confidently 

 said that we know tlie general outlines of the growtli 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 oifurs 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 tliose Asterids which have a 

 nomadic brachiolaria.* 



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

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



The common species of Asterias found at Newport resembles closely 

 Asteracanthio)i beri/liniis of A. Agassiz, and has close alfinities with 

 Asterias viih/aris, tSL, and A. Forbes'd, Desoi'.f Although I suppose it 

 to be the same as herylhms, there are some peculiarities of coloration X 

 which would lead one to regard them as diti'erent. While the species 

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

 tures of both ,1. vttlyaris and A. Forbesil, it is not possible for me to 



* Our knowledge of tlie growth of tlie plates whicli form the mouth parts of 

 the staitish is fragineiitary and unsatisfactory. 



t Tlie genus Leptasterias is thought to be sufBcicntly 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 Astrracauthion palluhis, Agass., and Aatcra- 

 cant/lion hcrtjlinus, 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 tlie artificial imjjregnation of the starfish. 3Iany 

 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 s[)ecimens laid eggs in great numbers on .«everal occasions. Ova nearly 

 mature were also cut out of specimens of tiiis color. 



