12 MARINE INVERTEBRATA OF GRAND MAN AN. 



ECHINODERMATA. 



CRINOIDE.E. 



ALECTO ESCHRICHTII, Mull, et Trosch. The first specimen of the genus Alecto 

 or Camatula, so interesting to palaeontologists, yet taken on our coast, occurred to 

 me in twenty-five fathoms on a shelly ground near Duck Island. It seemed to be 

 a young individual, although nearly four inches in diameter. It was of a dark 

 green color, dotted with white; the disk grayish, and the dorsal-jointed append- 

 ages white. I have compared it with specimens of A. Eschrichlii from Greenland, 

 in the collection of Prof. Agassiz, and find differences which may be those of age, 

 since these latter specimens were all ten inches or more in diameter. Under these 

 circumstances, I have hesitated to describe it as new, though it may hereafter be 

 proved so, when more extended comparison shall be possible. 



EURYAL^E. 



ASTROPHTTON AoASSizn, St., Euryale scutatum, Gould, Inv. Mass, (non Blainv.). 

 Until within a few years, all the northern species of this singular genus were con- 

 founded by zoologists in one. They have now been separated by Miiller and 

 Troschel, and the Scandinavian naturalists; four species in northern Europe being 

 known, and one in Greenland, with which I have had opportunities of comparing 

 our species, and find constant differences. The disk of A. Agassizii is rather large; 

 the arms divide in two, just beyond their emersion from the disk, and then con- 

 tinue to .branch dichotomously till at their extremities the rays are slender rough- 

 ened twigs, which in preserved specimens are tangled and interlaced in every 

 direction, but in life are usually stretched out to their utmost extension. My 

 largest specimens were thus a foot and a half in diameter when alive, while in a 

 dried state they measure scarce a foot. The disk is quite regularly pentagonal. 

 On its upper surface the ten radiating ribs are narrow, prominent, and provided witli 

 numerous small, sharp, small-based warts, which are very irregularly scattered, and 

 which exist also on the marginal ridge which surrounds the disk, except on the 

 concave, which forms a sort of socket for the upper base of the arm. Between the 

 radiating ribs, the disk is soft and membranous, with few scattered granules most 

 numerous in a flat space in the centre. The disk, as well as the arms, is smooth 

 and glabrous below ; the mouth comparatively large, with small spines at the entrance, 

 and larger ones within. The arms are flat beneath, with steep sides and convex 

 upper surface. They are covered above with crowded minute granules, like fine 

 oolite, which are arranged in numerous, somewhat irregular transverse rows, and 

 decrease in number on the sides, the lower parts of which are smooth. On the flat 

 under surface the joints are indicated by the pores, which are arranged on each side, 

 in pairs ; there being also, just outside of each pore, a row of four small blunt spines. 

 The first pair of pores, however, next the disk, is unprovided with spines. There 

 is also in the angle of each of the bifurcations a single pore without spines. 



