7O VERRILL 



dorsal and lateral spines and also occur in clusters on the papular 

 areas. 



The interactinal spines form four or five crowded rows ; they are 

 large, stout, mostly clavate, with obtuse, smaller, often flattened, 

 striated or sulcated tips; those of the synactinal (inner) row are 

 less stout, but not shorter; those of the interradial areas are longer 

 and more fusiform. Toward the mouth the adambulacral rows of 

 ossicles are prolonged as a narrow ridge to the sunken mouth, unac- 

 companied by actinal spines. The actinal spines bear clusters of 

 minute minor pedicellariae. The interactinal ossicles, as exposed in a 

 denuded specimen, are small and closely arranged in about five rows 

 at the base of the arm, with some additional ones irregularly inter- 

 polated. Large, pedicelled, lanceolate major pedicellariae are attached 

 within the margins of the furrows. The marginal spines are capi- 

 tate and striated like the dorsal spines. 



VARIATIONS. 



In the Museum of Comparative Zoology I have seen two six- 

 rayed specimens (No. 1423) from Crescent City, Calif. These have 

 the dorsal spines unusually numerous, and strongly reticulated or 

 areolated. 



Two specimens sent to me by Mr. J. F. Whiteaves, of the 

 Canadian Geological Survey, from Vancouver Island, are remarkable 

 for their great size. They are 20 to 22 inches in diameter. Radii of 

 one are 75 mm. and 250 to 275 mm. ; ratios about i : 3.75. Radii of 

 the other are 70 mm. and 240 to 260 mm. ; ratios about 1 : 3.6. The 

 disk is abnormally flattened in both, by imperfect preservation. 



They agree with ordinary specimens in all essential features, 

 except such as are naturally due to greater size. The dorsal spines 

 are unequal and strongly clustered, but have lost more or less of 

 their reticulated arrangement, except distally, owing to the breaking 

 up of many of the lines of spines and the interpolation of new 

 clusters. The spines and pedicellariae are of the ordinary forms. 

 The large, serrate pedicellariae are very abundant on the dorsal, 

 lateral, and actinal surfaces. The largest are on the actinal inter- 

 radial areas, where some equal the spines in diameter. 



Mr. Whiteaves also sent a short-rayed specimen, from the Queen 

 Charlotte Islands, which has the dorsal spines larger, more capitate, 

 and more numerous than usual, so that they form very prominent 

 nodular clusters and imperfect reticulations. Its large unguiculate 

 pedicellariae are unusually abundant. (Var. nodiferus.) 



