700 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxn. 



Calcareous ring very flexible and delicate, the radial and interradial 

 pieces being joined apparently in one continuous piece; at all events, 

 the line of demarkation is invisible. Form of ring is shown by figure. 

 (Plate LXXIV, fig. 2a.) Anterioredgeof pieces isso thin thatitappears 

 scarcely more than a translucent deposit of lime in the membrane; but 

 the core of both radial and interradial pieces is thicker and is indicated 

 by the lightly shaded portions of figure. Madreporic canal is of con- 

 siderable thickness, running forward in dorsal mesentar}^ and entering 

 the body wall on level with calcareous ring. One rather large Polian 

 vesicle. Ring canal and adjacent portions of radial canals conspicuous. 

 Gonad forms two tufts on either side of dorsal mesentery, just behind 

 ring canal, the genital duct running forward beneath madreporic canal. 

 Walls of gonad contain comparatively few irregular thorny or slightly 

 branched rods. Longitudinal muscle bands thin and weak. 



Ventral perisome contains smooth robust rods dichotomously 

 branched at extremities and with one to several perforations at the 

 tips. The majority have the simpler form shown in figures, but many 

 jvre thrice branched. The simpler forms usually have no terminal 

 perforations. These rods vary from 0.4 to 0.57 mm. in length. Com- 

 paratively few are slightly longer. The figures were drawn from 

 deposits along midventral line. Dorsal perisome is rendered rigid by 

 long, stout, smooth, simple rods with the tips expanded and perforated; 

 or the tips may be divided and each division slightly expanded and 

 perforated. Fewer rods are branched at one end onl}^, the branches 

 being fairly long. Besides these there are comparatively few rods of 

 robust form once or twice dichotomously branched, similar to but very 

 much larger than some of the ventral deposits. These are usually 

 symmetrical at either end and the tips are expanded and several times 

 perforated. The simple rods are much the more numerous and meas- 

 ure about 0.95 to 1.3 mm. in length; some are as short as 0.8 mm. 

 Rods branched at one end only are about 1.6 mm, long; those branched 

 dichotomously vary from 0.9 to 1.3 mm. Rods in lateral and dorsal 

 papillae are of the same form but dift'er in size, those of the former 

 being slenderer. The rods are simple, expanded at the tip into a 

 spoon-shaped blade, many times perforated. Rods at base of lateral 

 papillae are remarkable as to size, many measuring 3.5 mm. in length. 

 (Plate LXXV, fig. 1^.) Atabout middle they measure 1.6 mm. and grad- 

 ually diminish in length and caliber toward extremity, where they are 

 about 0.65 to 0.95 mm. long, and very slender (fig. Ic). Indorsalpapilljea 

 few of the basal rods attain a length of 3.2 mm. Thej'^ are practically 

 identical with those of lateral papillte. Rods in pedicels are curved 

 and branched slightly at tips, occasionalh" with a perforation or two. 

 The longest measure about 1 mm., the shortest about 0.2 mm. Rods 

 in walls of gonad are irregular, about 0.2 to 0.4 mm. in length, with 

 scattered prominent thorns and occasionally one or two short branches. 



