264 BULLETIN 82, UNITED STATES NATIONAL MUSEUM. 



outer side very broadly rounded, and that between the base and the inner side a 

 right angle, and even sometimes less than a right angle; occasionally the covering 

 plates may be truncated distally, or they may take the form of elongated hexagons. 

 The tentacles have a rather broad band of interlaced spicules along the 

 distal side. 



Chlorometra garrettiana. The side plates, -which are of the usual structure, 

 are as broad at the base as the height to the apex of the median obtuse angle on 

 the distal edge; the notch between the median angle on the outer edge and the 

 distal process is deep and almost semicircular; the notch on the distal side below 

 this distal process is deep, and usually semicircular; the inner proximal angle is 

 slightly produced, so that, viewed laterally, there is a deep concavity between this 

 angle and the base of the broad proximal projection ; in ventral view the outer edge 

 of the side plates is a thick semicircle, the proximal end of which extends farther 

 inward than the distal; the inner ends, adjoining the pinnulars, are also thick 

 semicircles; the inner side of the side plates shows two high, broad ridges, one 

 passing along the narrow distal process and usually disappearing at the notch on 

 the distal side, the other running directly downward perpendicular to the base 

 from the attachment of the covering plate as far as the notch on the proximal side, 

 then curving about and running to the proximal inner angle. 



The covering plates are broadly rounded, about as long as broad. They are 

 not quite symmetrical, the inner side in its proximal third becoming straight and 

 running downward parallel to the median keel to the rounded right angle between 

 the base and the inner border ; the opposite side is a segment of a circle. In some 

 cases the outer half of the covering plate is a semicircle, from which the sides con- 

 verge in almost straight lines to a short straight base, the outer side being flatter 

 than the inner. 



Strotometra hepbumiana (figs. 808-811, p. 385). The side plates are small and 

 delicate, rather coarse in texture, with somewhat ragged edges. The general struc- 

 ture is as in related species ; in lateral view the side plates are roughly oblong, half 

 again as broad as high, the distal border slightly concave, the proximal with a 

 notch in the proximal portion just below the middle, or with the whole proximal 

 half concave ; the outer distal angle is slightly produced : the outer proximal angle 

 is slightly produced and broadly rounded ; a low obtuse angle occupies the middle 

 of the outer border. 



The covering plates are reniform, very broadly rounded, slightly broader than 

 long, the inner point where the inner edge passes over into the base almost a right 

 angle, the outer border curving in a wide semicircle from the distal border to the 

 point of attachment. 



Charitometra basicurva (fig. 1167, pi. 27). 



Family ANTEDONID^E. 



Antedon petasus (figs. 784-786, p. 366). Normally each ambulacral lappet 

 contains a short, usually straight, rod which is not longer than the length of the 

 sacculus: these alternate with the sacculi, and their inner ends are just within a 



