I08 VERRILL 



become much more numerous and more conspicuously clustered 

 than in those of the ordinary sizes. 



The upper and lower marginal spines are conspicuously longer 

 than the dorsals and are usually tapered. They commonly stand 

 singly on each plate and form a simple row in each series on the 

 basal part of the rays, but distally the upper row usually becomes 

 double, with two spines on each plate. A short lateral row is often 

 interpolated between the two marginal series. 



The actinals are like the marginals and form one continuous and 

 usually simple row, close to the lower marginals. The marginal and 

 actinal plates are stout, wide, and closely joined. 



The subactinal spines are rather smaller and do not usually extend 

 beyond the basal third of the rays; they are close to the adambula- 

 crals. The latter are biserial, but an occasional plate bears but one 

 spine; they are slender, tapered, and terete, and carry conspicuous 

 clusters of minor pedicellaris. 



The major pedicellariae of the Labrador borcalis are very variable 

 in size, just as Stimpson describes those of acervata. Those scat- 

 tered on the back are very small, short-ovate; those on the lateral 

 channels are much larger, but not unusually large, and vary from 

 short-ovate to triangular-ovate; most of them are short, with very 

 obtuse tips, and are not distinctly serrate externally. Some speci- 

 mens have only a few of these pedicellariae, and of smaller size than 

 usual. 



The color in life varies from pale red or pink to purple and pale 

 violet. 



The name A. polaris is preoccupied by Asterias polaris Sabine, 

 1824. 



The original type of Dr. Stimpson's Asterias acervata is still pre- 

 served in the U. S. National Museum. Photographs of it have been 

 sent to me by Dr. R. Rathbun for reproduction. (See pi. xxvii, 

 figs. I, 2.) 



Dr. Stimpson gave the following description : 

 "Rays six, more convex and more tapering than in A. polaris. 

 Disc of moderate size. Proportion of the diameters, i : 4.5. Ambu- 

 lacral spines in two rows (two to each plate), rather stout, cylin- 

 drical, and thickly covered with minor pedicellariae near the tips. 

 Ventral spines standing in two or three irregular rows. Lateral 

 channel not well marked, and sometimes occupied by very small 

 spines. Lateral spines standing singly in one row, and more pointed 

 than the ventrals. Dorsal spines more numerous and crowded than 



