556 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Description . — Rays normally 5, occasionally 6. The proportions vary to an extraordinary degree. 
R=30 to 60 mm., r=6 to 13 mm., R=2.5 to 5.5 r. Breadth of ray near base, 10 to 14 mm., 
R=2.4 to 5.4 br. Rays varying from nearly cylindrical to long conical, but usually with a rounded 
tip, and not flattened. The basal part is oftentimes swollen and then contracted close to the disk, i 
which is of very variable size. Interbrachial arcs are sometimes rounded, but more often acute. i 
Abactinal surface covered by a network of plates, which form a more or less firm skeleton, according 
to the size of the meshes, these ranging from under 0.5 mm. to over 1.5 mm. As a rule these plates have 
no regular distribution, but in some specimens there is, on the sides of the ray, an approach to a trans- 
verse arrangement, either in vertical or oblique rows. Upon the plates are numerous minute spines, 
which differ greatly in size and form in different individuals. They are sometimes very delicate and 
sharp, sometimes stout and blunt, and the length varies from 0.2 to 0.5 mm. These spines occur singly; 
or more often in groups of from 2 to 12, and as they are so small, so numerous, and of such nearly uniform 
length (in any one specimen) the surface of the ray does not appear spinulose in the living animal. 
On the actinal surface the plates tend to form longitudinal rows, especially near the base of the rays, 
and there is almost invariably one well-defined row just outside the adambulacral plates. The latter 
are not very numerous, a ray 42 mm. long having only about 65 on each side of the furrow. The 
armature of the adambulacral plates is made up of 10 to 12 blunt spines, of which 1 is on the side of 
the plate, well up in the furrow, while the remainder are on the face of the plate. Although they ; 
vary considerably in size, in different specimens, the arrangement, on the whole, is fairly constant. 
The furrow spine is very slender, but is sometimes quite long, over 0.5 mm. Of the others, that nearest 
the furrow is the largest (1.5 mm.) and usually stands more or less alone. Behind, or outside of it, 
are 1 or 2 a trifle smaller, and the remainder, arranged more or less irregularly in pairs, diminish 
rapidly in size, so that those on the outer edge of the plate are of about the same size as the spines on 
the adjoining plates. In young individuals the adambulacral spines tend to form a narrow, transverse 
series on the plate, continuous with the transverse series on the sides of the ray, but in adults such an 
arrangement is obscured, if not obliterated. Oral spines long, but not peculiar. Papular areas small, 
with usually 1 papula, sometimes 2 or 3. Madrepore plate small, with few wide furrows, the ridges 
between which frequently bear spines. Feet biserial. Color in life,' abactinally usually bright red, 
with a slight orange cast, the actinal surface deep yellowish. There is, however, more or less variety. 
In some specimens the red is faded in spots to yellowish, or even the whole abactinal surface to orange, 
yellow, or cream color; in other specimens the red is deepened to purple, often of a very rich shade, 
while again the purple is faded to lavender or nearly white. 
Range . — Greenland and Labrador to Connecticut, off New Jersey, and even Cape Hatteras; littoral 
only as far south as the Woods Hole region; northward it is common from low water to 220 fathoms, 
while southward specimens have been reported from 1,350 fathoms. Also Spitzbergen, Nova Zembla, 
and Iceland to Great Britain and northwestern France. Northwestern coast of Asia (Brandt), Bering 
Sea (Ludwig). 
Remarks . — The abundance of this star-fish in Woods Hole Harbor varies greatly in different years, 
and although it is often common the specimens are always small. Much the finest specimens found 
in this region come from Crab Ledge, where the species is very common, and exhibits the greatest 
variety of form and color. Careful measurements were made of 142 specimens to see whether there 
was any tendency to diverge into two or more forms, but none appears. While some specimens have 
the breadth of the ray over 36 per cent of the length, others have it only 18 per cent, while the majority 
range about 28 per cent. The curve of variation falls off quite uniformly in both directions. Nor 
could 1 find that the diversity of either form or color was in any way correlated with age, sex, or 
environment. This species breeds in the early spring; the eggs are large and contain much yolk; 
development is abbreviated, but is still imperfectly known. 
6. Solaster endeca (Retzius). (PI. 3, figs. 12,13; pi. 4, fig. 23.) 
Asterias endeca Retzius, 1783. 
Solaster endeca Forbes, 1839. 
Description . — Rays usually 10 or 11, frequently 9, occasionally 7, 8, 12, or 13. R=75 to 150 mm., 
r=25 to 50 mm., R=3 r. Breadth of ray near base 12 to 30 mm., R=5 to 6 br. Rays arched 
abactinally, flattened actinally, regularly tapering, bluntly pointed. Disk large, generally highly 
arched; in a specimen with R=106, the disk is 35 mm. high. Interbrachial arcs rather rounded. 
Abactinal surface covered with a very close net-work of plates; making a firm skeleton. These plates 
