258 BTJLLETIN 82, UNITED STATES NATIONAL MUSEUM. 



Oceanometra annandalei. — The side and covering plates in this species resemble 

 those of O. gigantea. 



The perisome over the genital glands is incased in well-formed and definite 

 plates of very different sizes and shapes, some of which, near the borders of the 

 pinnulars, are longitudinally elongated. 



Thalassometra villosa (figs. 823, p. 392, and 879, 880, p. 435).— In direct lateral 

 view the outline of the side plates is trapezoidal, the inner side, adjoining the pin- 

 nulars, being the longest; the proximal side is perpendicular to the inner side, 

 nearly or quite straight, with a prominent notch just below the middle; the outer 

 side is of about the same length as the proximal, and has the form of a broadly 

 obtuse reentrant angle; the distal border leans proximally at an angle of slightly 

 more than 45°, and usually joins the inner side in a broad curve; whereas the inner 

 edge of the side plates is parallel with the edge of the pinnulars, the outer edge 

 makes with it an angle of about 45°, the proximal end being much nearer the middle 

 of the pinnule than the distal. On the slanting outer border of the side plates, 

 slightly more than half way between the inner and outer ends, is a narrow covering 

 plate, which projects from it at right angles in lateral view, and in ventral view is 

 seen to be approximately at right angles to the outer edge; it is articulated to a 

 slightly thickened portion of the border of the side plate. 



The covering plates are shaped like a pimipkin seed, with the pointed end 

 inward toward the center of the pinnule. Their lower edge shows a very obtuse 

 angle, by which they are articulated to the middle of the obtusely angular excision 

 of the outer edge of the side plates. 



The perisome over the genital glands is completely covered by thin plates of 

 very diverse form and size. 



Thalassometra agassizii (figs. 1171, 1172, pi. 27). 



Aglaometra eupedata. — The side and covering plates resemble in all essentials 

 those of Daidalometra hana; the thin proximal process is turned inward at an 

 angle of about 45°, reaching as far as the midline of the covering plate; the 

 proximal portion of the side plate, which bears the covering plate, is turned inward 

 at about the same angle. In both cases the torsion is in the outer two-thirds of the 

 plate, so that in this part the central portion of the plate is very convex exteriorly. 



Aglaometra incerta (fig. 1166, pi. 27). 



Family CHARITOMETRID^. 



Crossometra helius (fig. 867, p. 419). — In direct lateral view the major portion 

 of the side plates is seen to be practically square, with the proximal outer angle 

 broadly rounded off and the distal outer angle, at the base of the process to be 

 described, raised into a slight obtuse angle ; the distal outer corner is produced dis- 

 tally and outwardly in the form of a narrow curved horn; the outer half of the 

 proximal border is produced laterally and slightly outwardly for a distance about 

 equal to two-thirds of the transverse diameter of tlie plate. Large and prominent 

 sacGuli occupy the broad gaps between the apposed outer processes of adjacent 

 plates. Viewed from beneath the inner ends of the side plates are seen to carry at 



