NO. 1555. HAWAIIAN H0L0THIJR1A:<S— FISHER. 668 



spire made up of four rods, one crossbeam, and a crown ending in 

 twenty to thirty teeth. Supporting rods of pedicels smooth, dilated 

 at the ends and in the middle, where there are several perforations. 

 Color of a well preserved specimen: ground color a grayish white, 

 with a faint suggestion of green, dotted minutely with fine brownish 

 specks. Along the l)ack are two rows of brown spots, fifteen to a row. 

 The fine dots are inconspicuous and less numerous on the ventral than 

 on dorsal surface. Length 145 mm., breadth at middle of body 22 nun. 



Z^>tv7//V//.— Honolulu, reef, 2 specimens. 



Near the extremities of the bod}^ on the ventral surface one can 

 distinguish an irregular arrangement of pedicels in four rows. Near 

 the middle this is not so obvious. The two ventral ambulacra are well 

 marked, however, a line and a narrow area free from pedicels passing 

 along the middle of the abdomen. I have not examined a specimen 

 of iiionacar!a which has the ventral pedicels in three rows, so do not 

 know how much more obvious the arrangement may be in that species. 

 A second and smaller specimen oi arenlcola has the general tint of the 

 body light brownish and the dark purplish-brown dots much more 

 conspicuous than in the first example. The large spots on the back 

 are ratlier broken up, consisting of accunmlations of smaller spots. 



The calcareous ring is rather small. The radial pieces are a trifle 

 longer than broad, truncate anteriorl}^, with the usual obtuse incision, 

 which is small. Interradial pieces very nuich smaller than the radial, 

 althougli about of the same width. They have one anterior tooth, 

 while the posterior border is rather conspicuously excavated; that of 

 the radialia less so; one Polian vesicle; one madreporic canal, free, on 

 the right side of the dorsal mesentery. This agrees with Lamperfs 

 diagnosis. Theel mentions two Polian vesicles and a bunch of three 

 small madreporic canals in a Samoan specimen. One of the specimens 

 examined has no Cuvierian organs. 



The oval, smooth Imttons are ver}^ numerous. They vary slightly 

 in length, 0.065 to 0.068 mm. l)eing the average. The width is also 

 variable, 0.027 to 0.0325 nun. being coiimionest. Although six regu- 

 lar holes are the rule, eight also occur. The disk of the tables has a 

 smooth border and is quadrate-circular in outline. The commonest 

 form is figured (Plate LXVIII, tig. 5). Occasional!}' there are more 

 peripheral holes, but the regular form is remarkabh' constant. View- 

 ing the disk from the l)ottom, the large central hole might be inter- 

 preted as four holes, on account of the spire rods. Viewed from the 

 side the tables resemble those of //. impatiens with one crossbeam. 

 The disk, however, is altogether difiereut. The spire is about 0.046 

 mm. high, while the diameter of the disk varies from 0.051 mm. to 

 about 0.065 nnn. The number of teeth crowning the spire is Aariable, 

 but always more than twenty. The supporting rods of the pedicles 

 are smooth, often more simply or more elaborately perforated than 



