732 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxii. 



rior half of body. Anteriorly thej^ are scattered, often encroaching 

 upon radii; posteriorly they form a very irregular zigzag series; 

 sometimes very f6w posteriorly. PapilUe unequal in size. Deposits: 

 Wheels and numerous scattered, small, slightly curved, and C-shaped 

 rods, swollen or knobbed at the tips, together with straight rods 

 forked at one or l)oth ends. In tentacles are numerous larger, more 

 elaborately branched rods. In addition numerous small oval grains, 

 or grains SAVollen at both ends and constricted in middle, are found in 

 longitudinal muscles. Body wall thin, translucent. Color in life, 

 between burnt carmine and pomegranate purple, translucent. Wheel 

 papilla? light 3"ellowish red. Length, 15 to 45 mm.; breadth, 2 to T 

 mm.; usually broadest posteriorl3\ 



Locality. — Reef ])etween Honolulu Harbor and Waikiki, Oahu, in 

 tide pools. The animals live a few inches beneath the surface of the 

 soft, sandy bottom of numerous tide pools and are very common. 

 About 125 specimens. 



Type.—G^t. No. 21230, U.S.N.M. 



In general form the body is cylindrical, often, but not always, 

 broader posteriori}^ than anteriorl3\ Posterior extremit}' rounded to 

 truncate, depending upon the degree of contraction. Tentacles are 

 about 2.5 nmi. long and the two terminal digits about 0.5 to 0.57 mm. 

 The number of digits is constantly 8 to 10, the same individual having 

 tentacles with 8, 0, or 10 digits. In the case of 9 digits there are two 

 enlarged terminal ones, just the same as when an' even number is 

 present. The number of tentacles is very rarely 13. In a large num- 

 ber counted onl}^ one individual was found which thus departed from 

 the normal number. As noted in the diagnosis, there is a single series 

 of spaced wheel papillre on each of the two ventral interambulacra, 

 but in posterior half of body these papilla? are very few or are want- 

 ing. There are rather more papilUe on middorsal interambulacrum 

 than on the two dorso-laterals, although the difference is not great. 

 In some individuals a rather irregular series is formed along the three 

 interradii, but generall}^ the papilla? are scattered so that no regular 

 serial arrangement is discoverable within each interambulacrum. The 

 wheel areas under the microscope are seen to be circular or elliptical, 

 usually the latter, and range from 0.21: to 0.6 mm. in diameter. 



Calcareous ring (Plate LXXXII, lig. 3<'/) does not possessany peculiar 

 characters. Madreporic canal single, in dorsal mesentery. Polian 

 vesicles, 11 or 12, of which 4 are considerably larger than the rest. 



The wheels (Plate LXXXII, tig. 3) vary in diameter from 0.015 to 0.1 

 mm., many sizes being found within a single group, where they are 

 packed several layers deep. The small curved rods vary in length 

 somewhat, the commoner lengths ))eing found between 0.03 and 0.016 

 mm. The tips and sometimes the middle are slightly swollen, the 

 former being provided with incipient thorns in some cases. The forked 



