648 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.xxxii. 



along- a median longitudinal and U\o lateral areas, although these areas 

 do not appear sharply defined by any means. 



In the laroe specimen dissected there is but one madreporic canal, 

 situated on th« right side of the mesentery. The madreporic body is 

 eh)ngat(> ((> nun.) and is perfectly free in the body cavity. There is 

 but one Polian vesicle. Calcareous ring without posterior prolonga- 

 tions. The radial pieces are considerably larger than the interradial. 

 Genital glands form a large tuft on the left side of the dorsal mesen- 

 tery. Right ))ranch of respirator}" tree longer than left, reaching to 

 calcareous ring. Cuvierian organs present at left side of base of 

 respii'atory tree; tuft rather small. 



Tlie calcareous deposits are numerous Init of a simple nature, con- 

 sisting of straight or slightly curved, rather linelj" granulated rods, 

 the granulations assuming the form of irregular protuberances at the 

 ends. In the dorsal perisome the rods average slightly larger than in 

 the ventral. They vary from 0.08 to 0.12 mm., the former being the 

 average. Many are as small as 0.05 nuu., and the smallest are about 

 0.03. Occasionally the rods are forked slightl}' at one or both ends. 

 The rods of the ventral perisome average between 0.0.5 and 0.07 mm. 



This species is apparently confined to the Hawaiian group. No 

 specimens, however, were taken in the Windward Islands, where it is 

 likely the type was secured. 



ACTINOPYGA MAURITIANA (Quoy and Gaimard). 

 Plate LXVII, figs. 1, In-d. 



Holothurm. mauritkma Quoy and CrAnrARn, Voyage de I'Astrolabe Zoologie, IV, 

 Zooi)liytes, 1833, p. 138. 



Bod}' elongate, robust, broadest posteriorly, or sometimes nearer 

 middle, usually slightly constricted near anterior end. Mouth usually 

 distinctly ventral, surrounded in life by a conspicuous, papillose collar. 

 Anus terminal, with five white calcareous teeth. Tentacles about 

 twent3'-tive (twent3'-two to twenty -six), rather crowded, broadly pel- 

 tate, the crests arranged in two irregular, concentric rows. Peristome 

 broad. Pedicels densely crowded, and without order, confined to the 

 flatfish ventral surface. Dorsal papilhe much fewer than pedicels, 

 about the same size and irregularly scattered. Integument tough and 

 leather3\ Deposits: In the dorsal integument longer and shorter rods, 

 with small processes along the sides and with the ends dichotomous or 

 spinous, together with numerous, much smaller rosettes, usually not 

 A'cr}' intricate; in the ventral perisome small, smooth, oval grains 

 and larger un])ranched rods with the ends slightly roughened. Ven- 

 tral deposits much more numerous than dorsal. Color variable, 

 usually an olivaceous brown, the l)ases of the papilla? encircled with 

 whitish; blotched Avith whitish along the sides and distad (see p. 649). 



