SHALLOW-WATER STAKFISHES l8l 



ginals ; each corresponds to five or six adambulacrals. Most of these 

 bear two long, tapered spines, usually blunt and somewhat flattened or 

 sulcate at the tips, rather larger than the upper marginals, usually 

 7 mm. to 8 mm. long. Between their bases there are often scattered 

 large and strong denticulate major pedicellariae, similar to those of the 

 back, but mostly stouter and more obtuse ; with these are some that 

 are much smaller, lanceolate, and subacute. The large pedicellariae 

 also occur on the naked lanes below, both on the papular areas and on 

 the adambulacral plates. There are a few small, thin, synactinal 

 ossicles connecting some inferomarginals to the adambulacrals, but 

 not bearing spines. The adambulacral spines form two regular close 

 rows, two on each plate; they are slender, tapered, mostly flattened, 

 subacute, about 5 mm. to 5.5 mm. long. The ambulacral pores are 

 large and form four rows. 



The dorsal minor pedicellariae are remarkable for their great size 

 and abundance ; in life they probably nearly conceal the whole upper 

 surface and spines, and are borne on slender pedicels. Their blades 

 are strongly bent and very strongly dentate. They are much like 

 those of 0. forreri. 



Their jaws are slender, strongly arched, open widely and usually 

 have thin, sharp, spatulate tips, that look like sharp hooks, when 

 seen in profile. They are about i mm. in height. They are not very 

 unlike those on U. linckii, but much larger. Color (when dry), gray- 

 ish brown above, dull yellow below. 



The type was from Departure Bay, British Columbia, 18 fathoms, 

 gravel (C. H. Young, Canadian Geological Survey, September, 

 1908). The disk was not sent to me. Five loose rays were received. 



Although this subspecies is somewhat allied to U. linckii, and re- 

 sembles it in form and the arrangement of the dorsal spines, it differs 

 widely in several characters. U. linckii has more numerous and 

 larger sacculated spines. It has large groups and wreaths of minor 

 pedicellariae of unusually large size, but they are not half so large as 

 in this species and are far less abundant dorsally, the larger wreaths 

 being on the lateral spines. They also differ in form. The large, 

 denticulate major pedicellariae are also abundant on U. linckii, dor- 

 sally, laterally, and in the grooves (intra-ambulacral), but they are 

 not half so large in this species. In the former the adambulacral 

 plates and spines arc much less numerous and less crowded, so that 

 only about four of the plates correspond to one inferomarginal, while 

 in this species there are six or seven to one inferomarginal. In 

 U. linckii each adambulacral, on the proximal half or more of the 



