new Starfish and new Brittle Stars. 121 
The radial shields are large and are roughly ovoid in 
outline. From a point at the base of the arm they curve 
regularly outward to the median interradial plates, their 
free borders supporting the outer two or three marginal 
plates ; from their broadly rounded ends they curve inward, 
their inner sides being approximately parallel, until the 
level of the inner end of the median broad plate of the 
interradial column is reached, when they curve more rapidly 
inward and then outward to the arm-bases. 
An elongate, rounded, triangular plate separates the radial 
shields, except just at the arm-bases. 
The interradial portion of the disk between the distal 
portion of the radial shields is covered with a large single 
plate about half as large asa radial shield, which has strongly 
slanting sides and a curved inner border, which is about as 
long as the two lateral borders or half as long as the outer 
border. This plate (which supports the two central pairs 
of marginal scale-like plates) is joined with the plates of the 
central region of the disk by a triple column of plates, con- 
sisting of a broad and elongate central plate, on either side 
of which is a column of two (rarely three) similar plates 
placed end to end only half as broad as the central plate. 
The ventral interradial areas of the disk are occupied by 
ten or a dozen plates, usually two or three large ones on 
either side, with an irregular column of much smaller plates 
between them. 
The genital slits are long, extending from the side mouth- 
shields nearly to the edge of the disk. The genital plates 
are prominent, rather wide, reaching from the lateral border 
of the oral shields to the periphery of the ventral surface, 
increasing in width outwardly. 
The oral shields are transversely oval, about twice as 
broad as long, the proximal border forming a slightly obtuse 
angle. 
The side mouth-shields are very narrow, in contact in- 
wardly, running slowly to a point at the base of the genital 
slit. 
The mouth-papille form a narrow continuous band of 
uniform height, with a straight outer profile ; they are six 
in number, the innermost about as long as broad, the next 
three increasing regularly in length, and the two outermost 
much longer, about four times as long as high. 
There are from two to four conical tooth-papille. 
The teeth are long and sharp, triangular. 
The upper arm-plates are very narrow, triangular, about 
twice as long as broad ; the outer border is rounded, in 
