Clark — Six New Starfishes from the Gulf of California. > 53 



times two or four) alternating rows of short stubby well spaced truncated 

 spines which increase slightly in diameter from the base to the broad 

 nearly flat tip, and are about as high as, or slightly higher than, their 

 basal diameter ; in the interbrachial arc there are about twelve of these 

 spines to a row, and on the outer part of the arms eight or nine; those 

 in the median row are slightly larger than those in the lateral rows. The 

 channels between the superomarginals are filled with very numerous 

 short very slender spinelets w'hich are almost or quite concealed from 

 view by the outermost rows of spines on their outer surface. 



The line of union between the superomarginals and the inferomarginals 

 is slightly sunken. 



The inferomarginals correspond to the superomarginals, which in 

 general they resemble ; but in addition to the armature as described for 

 the latter they possess on the outer border of the actinal surface, or more 

 or less below the middle of the plate, a broad extremely flattened truncated 

 spatulate spine from 1 mm. to 1.5 mm. in length, about half as broad as 

 long or even shorter, increasing more or less in length from the base to 

 the tip, with more or less convex sides. In the interbrachial arc there 

 may be two or even three of these spines to a single inferomarginal ; 

 beyond the proximal third of the arm they become smaller, at the middle 

 of the arm being but little larger than the short spines covering the outer 

 surface of the plate, soon after disappearing altogether. 



The actinal intermediate areas are moderate in size; the plates are 

 arranged in regular series running from the inferomarginals to the corres- 

 ponding adambulacrals ; an unpaired line of plates runs from the mouth 

 plates about half way to the marginals. A single series of actinal inter- 

 mediate plates extends to the twentieth inferomarginal, a second to the 

 twelfth, and a third to the seventh. These actinal intermediate plates 

 are narrow, with deep channels between the rows which are filled with 

 small slender spinules similar to, but fewer and coarser than, the spines 

 filling the channels between the marginals. Each plate bears on its 

 actinal surface usually from four to eight short truncated spines, similar 

 to those on the marginals but more spaced, and of various sizes instead 

 of uniform, or nearly uniform, size. All of the plates bordering the 

 adambulacral and mouth plates, and a few of the others, bear pedicel- 

 larise, usually with three or four jaws. 



The adambulacral plates bear on their sharply angular furrow margin 

 three broad and strongly flattened spines. The innermost of these, 

 situated at the apex of the angle, is slightly recurved, and is flattened 

 transversely to the furrow ; the spines on either side of this are straight, 

 slightly less broad, and the axis of their flattening is parallel with the 

 edge of the plate so that they make an angle of 30° with the axis of 

 flattening of the median spine, or of 60° with each other. Behind these 

 is a row of two or three similar flattened spines, the axis of the flattening 

 being parallel with the furrow ; but one or both of the outer of these may 

 turn more or less so as to form supplementary furrow spines, and the 

 central one may become enlarged, especially toward the end ol the ray. 

 Beyond these is a row of two similar, but smaller spines. The grooves 



