174 BULLETIN 76, UNITED STATES NATIONAL MUSEUM 



ally slenderer. The spines are longitudinally channeled or striated, the furrows 

 varying in depth.. They are less evident in the type than in some large examples 

 from Monterey. There are ordinarily three or four longiseries of actinal spines in 

 the common medium-sized examples found in tide pools. Two specimens of the 

 heavier-spined form with R 55 and 80 mm. have two series. A large specimen of 

 i he typical form from Monterey (R 215 mm.) has three, while one with R only 120 mm. 

 has four. The typo (Tomales Bay) has six actinal spines in a transverse series on the 

 broadest part of ray and four at the middle. These actinals are clavate with usually 

 a sulcus on tho external face. Verrill (1914, p. 87) mentions a specimen of "liiikenii" 

 from off Monterey having R 284 mm., in which 



The proximal inferomarginal and most of the actinal plates bear two, three, or even more, stout, 

 often divergent spines, so that one can count eight to ten of these spines on each irregular trans- 

 verse scries. But one ray (doubtless a reproduced one) is only about two-thirds as long as the rest, 

 though nearly as stout; on this the ventral spines form only four or five rows, though similar in 

 size. On the distal half of all the rays the ventral rows decrease to about four to six. the plates 

 ring only two spines, or but one. 



Adambulacral spines, similar to those of ochraceus, in a single close series. In 

 the typical form the spines are slender, very slightly flattened and tapered, or mixed 

 tapered and untapered, round-tipped (blunt) with or without a depression at the 

 tip suggesting an incipient groove. In the larger-spined form the spines are more 

 evidently flattened with a slight groove on the outer side toward the tip. On the 

 narrow adoral carina the spines usually lengthen, become slenderer, and near the 

 mouth plates stand single file. On the ray the adambulacral spines stand very close 

 to the inner series of actinals, to which they are about equal in length. 



The mouth plates have the usual Pimster armature of a longer, usually tapering, 

 subacute, blunt, or subtruncate actinostomial spine, with a very short lateral com- 

 panion; and a prominent, tapered suboral, somewhat stouter than the innermost 

 adambulacrals. The Monterey specimens present numerous variations in the rela- 

 tive size and shape of the spines. 



Madreporic body large, exposed, situated less than one-half r from center of 

 disk; striae fine, irregular. 



Crossed pedicellariae (pi. 73, figs. 5, 5a) are smaller than those of capitatus and 

 typically more numerous. The majority occur in the circumspinal wreaths of the 

 abactinal and inferomarginal spines and in the external clusters of the inferomarginals 

 and actinals, but occasionally small clusters of them are found between the dorsal 

 spines, though not so commonly as in ochraceus. The pedicellariae of both large 

 and medium-sized specimens from Monterey Bay measure 0.27 to 0.31 mm. in length, 

 while those of the type (which is very large) vary from 0.27 to 0.34 mm., with a few 

 as large as 0.4 nun. 



Straight pedicellariae: (a) Very small broadly lanceolate pedicellariae (pi. 73, 

 fig. 56) about 0.15 mm. long are abundant on the thin integument of the papular 

 sw dlings and on the bases of the papulae themselves. Similar ones form conspicuous 

 pedunculate clusters or festoons here and there along the furrow face of the adam- 

 bulacrals, usually at the base of a conspicuous, often quite large, toothed pedicellaria. 

 The small ones are 0.15 to 0.2 mm. long and the large one about 1.5 mm., sometimes 

 smaller or larger. 



