658 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxii. 



Localities. — Puako Bay, Hawaii (lY), tide pools in lava rock; Napili, 

 Maui (2); Honolulu Reef (1); Waialua, Oahu (1); Kamalino Bay, 

 Niihau (1); La3'san Island, reef (1). Specimens examined, 23. 



The veiy dark color will serve as a distinguishing feature for this 

 species, the only other forms approaching- it in shade being //. ciner- 

 ascens and v<((/(thunda. II. fuscoruln-a is lighter and reddish. Along 

 the middle of the ventral surface I tind in most specimens a narrow 

 band free from pedicels. The papilUe vary greatly in the degree of 

 contraction, so that it is impossible to gain a correct idea of their size 

 from a preserved individual. The crowns of the tentacles appear 

 to be black to dark brown, but the peduncle is lighter, translucent 

 brownish. 



The radial pieces of the calcareous ring extend farther forward than 

 the interradial, and are of the usual type. The anterior edge has an 

 abrupt, rounded incision, while the interradial pieces have an anterior 

 tooth. The posterior edge of each piece is emarginated. Polian 

 vesicles two in one specimen examined. In another there are seven, 

 six of which are quite small. The madrepor c canals form a tuft on 

 each side of the dorsal mesentery, there being in one individual 

 examined eight canals to each bunch. The right respiratory tree 

 extends forward to the calcareous ring, and is tirml}^ anchored to the 

 body wall; the left is in connection with the extensive rete mirabile of 

 the intestine. No Cuvierian organs are present in several specimens 

 dissected. 



The tables are numerous, but not crowded, and each possesses a small 

 annular disk and a robust spire composed of four rods and one cross- 

 beam. The latter is rather nearer the disk than the crown. The spire 

 is surmounted by eight robust horizontal and four equally large 

 vertical teeth, three at each corner of the subquadrate crown. The 

 central hole of the crown is subcircular. Occasionally an extra tooth 

 is present. The disks are about 0.055 mm, in diameter and most com- 

 monly consist of a simple ring with a perforation at the base of each 

 spire rod. The spires are from 0.06 to 0.085 mm. high, and the 

 crowns about 0.06 mm. broad, over all. The plates are small and 

 irregular, varying in diameter from 0.019 to 0.045 mm. They are 

 thus smaller than the plates figured by Clark,'* presumably from 

 Atlantic specimens. The tables of the Hawaiian examples, on the 

 other hand, are larger, judging from the relative magnifications of my 

 figures and Clark's. The disks of the tables, however, average rela- 

 tively smaller to the proportions of the spire. The pedicels have a 

 well developed terminal plate, and the papilla^ a small one. Support- 

 ing rods are not a])undant in the papilhe. They are usually curved, 

 smooth (sometimes spinous) with the slightly dilated ends fenestrated. 



a American Naturalist, XXXV, p. 493, tig. 26. 



I 



