21)2 NEW STARFISHES AND OPHIURANS—VERRILL. 



and the ])roxiinal ends forming au acute angle, while the side arm- 

 plates meet more and more between them. 



The side arm-plates are large, thick, and prominent, separated by 

 deep farrows; on the ventral side they begin to meet at about the third 

 arm joint beyond the margin of the disk, and their length increases 

 rapidly until it becomes twice that of the ventral plates near the ends 

 of the arms; on the upper side they begin to meet at about the four- 

 teenth or fifteenth free arm-joint. 



In many of the larger specimens the dorsal plates are divided by an 

 irregular median furrow into two parts, and iu many specimens they 

 are again irregularly divided into smaller portions by one or two more 

 or less transverse furrows, so that they often appear as if composed of 

 four or five irregular pieces; but in other specimens of similar size the 

 plates are entire. 



The first ventral arm-plate consists of two small wedge-shaped pieces 

 between the innermost tentacle pores ; the next is much larger, about 

 as long as broad, a little thickened, somewhat shield-shaped, or pen- 

 tagonal, with rounded corners; the next is broad triangular, with the 

 outer margin strongly curved and the middle of the lateral margins 

 excavated for the second pair of tentacle pores, and the inner end nar- 

 row and slightly truncated ; those following become relatively wider, 

 broad triangular, with a strongly curved outer margin, incurved sides, 

 and more or less acute inner angle; beyond the middle of the arm they 

 become relatively smaller, \Andely separated, and the inner margin forms 

 a very obtuse angle. 



Color, in alcohol, dull grayis'.i or dirty brown. 



Variations. — There is considerable variation, even among the adult 

 si)ecimens, while the young, 8 to 10 mm. in diameter, differ iu many 

 respects from the large ones. The number and form of the mouth- 

 papillte and tentacle scales vary somewhat in specimens of the same 

 size. The mouth shiekls are sometimes more top-shaped or j)ear-shaped 

 than in the specimens described; the lateral margins being convex 

 witlj the corners rounded. The large plate at the distal end of the 

 month-shield is sometimes divided into two or three parts, most fre- 

 quently by the separation of the two inner corners as small triangular 

 plates. The two lower arm-spines are not always close together, and 

 sometimes four spines occur, the extra spine appearing either just below 

 the upper one or just above the second. 



In the young specimens, 8 to 10 mm. in diameter, the scaling of the 

 disk is much more regular, and the relatively large primary plates form 

 a pretty regular rosette. The mouth-shields are relatively shorter and 

 more top-shaped. The mouth-papillie and tentacle-scales are very reg- 

 ularly arranged and less numerous than in the specimens described. 

 The first complete ventral arm-plate is prominent and rounded; all the 

 ventral plates beyond this are separated by the side arm-plates. The 

 next three or four later.il arm-plates are broadly turbinate, with the 



