62 



CONNECTICUT GEOL. AND NAT. HIST. SURVEY. 



[Bull. 



In general it is possible to distinguish our two species by the 

 shape of the body, the arms being thicker at the base and more 

 pointed at the tips in the northern starfish (Plates VIII, IX), 

 while those of the common starfish are rounded and blunt at the 

 tip. The spines along the middle of the aboral surface of each 

 arm often form a conspicuous median row (Plate IX) extend- 

 ing the length of the arm, while those of the common starfish are 

 scattered more irregularly. 



Another specific distinction may be found in the shape of 

 the major pedicellariae, particularly those on the adambulacral 

 spines, as shown in Fig. 8. Instead of the broad, rounded 

 pedicellariae found in A. forbesi, many of those of the present 

 species have long and pointed blades. 



Fig. 8. Calcareous plates of pedicellariae of Asterias. A, major 

 pedicellaria, Asterias vulgaris; B, minor pedicellaria, A. tenera; C, major 

 pedicellaria, A. forbesi; D, minor pedicellaria, A. forbesi. All from 

 adambulacral spines. Enlarged 90 diameters. 



This species grows to a much larger size than does the com- 

 mon starfish, full-grown individuals often measuring eight inches 

 or more between the tips of opposite arms. Specimens more 

 than 16 inches in diameter have been recorded from Nova. 

 Scotia. 



The coloration shows great variation, yellow, yellowish brown, 

 orange, and purplish specimens being most abundant, although 

 shades of pink and red are sometimes present. The madreporic 

 plate is usually pale yellow. The spines are generally of lighter 

 color than the surface of the body. 



