Alcyonaria' G 43 



Keratoisis Wright. 



Keratoisis Wright, Ann. and Mag. Nat. Hist., II, 1869, p. 427; III, p. 24. 

 Gray, Cat. Lith. Brit. Mus., 1870, p. 18. Ceratoisis Verrill, op. cit., 

 1883, p. 11. 



In this genus the branches are usually few and distant and arise from the 

 calcareous joints. Otherwise it agrees verj' closely with some of the sparingly 

 branched species of Acanella. The calcareous joints are tubular. The cahcles 

 are strongly armed with large spiniforni spicules, and the coenenchyma also con- 

 tains large fusiform spicules. 



In this genus are included the largest known species of the family. Some 

 specimens of K. oniata are about four feet high. These are found at considerable 

 depths, in cold water, on the Banks off Newfoundland and Nova Scotia. 



Keratoisis omata ^''errill. Gold-banded Coral. 



Keratoisis omata Verrill, Ainer. Jour. Sci., vol. XVI, 1878, pp. 212, 376; op. 

 cit., 1883, p. 11, pi. I, figs. 4-4b (as Ceratoisis); op. cit., 1885, p. 533. 



Plate XVI; Figs. 1-lb. Plate XVII; Figs. 4-4b. 



Coral tall; sometimes over four feet high; distantly and irregularly liranched, 

 the branches spreading, often nearly at right angles, elongated, rather slender, 

 gradually tapering, giving off, in the same manner, elongated branchlets. The 

 branches and branchlets mostly arise from near the proximal end of the cal- 

 careous joints, but sometimes from the middle. The calcareous joints are 

 ivory-white, elongated, round, sHghtly enlarged at the ends, usually faintly and 

 often indistinctly striated longitudinally, appearing smooth to the linked eye, 

 but finely granulous under a lens; they are tubular, having a central tube equal 

 to about a third oi' a fourth of their total diameter. The chitinous joints are 

 usually lustrous golden yellow or bronze-color, sometimes plain brown, short, 

 scarcely longer than thick in the larger branches, about twice as long as thick 

 in the "smaller ones, where they become translucent and brownish or amber- 

 color, without the metalhc lustre seen in those of the larger branches. The 

 basal part is deeply divided into irregular, palmate, flattened IoIdcs, or root-like 

 expansions, by means of which it anchors itself in the mud. 



One specimen, preserved in alcohol, shows remarkable variations in the 

 length and form of the cahcles. Over most of the branches theyare very long 

 and prominent, constricted in the middle, with an expanded base and enlarged 

 summit crowned by eight prominent spines, surrounding the incurved and nearly 

 retracted tentacles (PI. XVII, fig. 4a) . In this form of calicle the length is two to 

 three times the average diameter. But on other branches the cahcles are only 

 prominent sub-conical verrucaj, broadest at base, with the summit narrow and 

 the spines but httle prominent (Fig. 4a); these are often about as broad as high 

 Intermediate forms also occur on this specimen. The cahcles are irregularly but 

 rather uniformly scattered over the whole surface, and are mostly separated by 

 spaces two or three times as great as their breadth, though some are in contact 

 at their bases. The surface of the crenenchyma and cahcles is covered with a 

 soft integument, which nearly conceals the spicules, except at the border of the 

 cahcles; but they become conspicuous when dried. , , , ^ . 



The calicles in dried specimens are usually promment, e ongated, somewhat 

 expanding toward the end, and are crowded nearly equally over the whole 

 surface; they are covered with large, conspicuous^ acute spicules which form, at 

 the summit: eight sharp spinous points. (See PL XVI fig. a). The coenen- 

 chyma is th n, translucent, yellowish, filled with long and large fusiform, spicules. 



