262 PR0CEEDING8 OF THE ACADEMY OF [May, 



ing from the middle of the three diverging ones, others expand into 

 an irregular disk, from which project from four to seven points 

 of different sizes and shapes. But the most remarkable spines are 

 those which protect the extreme posterior and external border of 

 the scale. These are very large and tree-like in form, and most 

 frequently branch in a fundamentally trifid, ternate plan, though 

 some of the branches may be bifid or even simple. The final 

 divisions are always acutely pointed. 



Setre of the dorsal and ventral fascicles are of approximately equal 

 length and thickness. The former are somewhat stouter basally, but 

 the latter are terminally, and their apices form a nearly regular out- 

 line, beyond which only one or two of the dorsalmost ueuropodial setse 

 project. The very numerous notopodial setve are arranged in many 

 rows and radiate in all directions, but chiefly laterad and caudad, 

 overlapping the following parapodium. Their form is character- 

 istic. The anterior dorsalmost ones (PI. XIII, fig. 3) are short, 

 stout and strongly curved. They are about two-thirds free, with 

 the inserted part suddenly contracted and narrow, and the thickest 

 region at about the middle of the free portion. There is a very 

 ■extensive spinous region, in which the rows of capillary spines are 

 rather close and long. The short, smooth end, which is equal in 

 length to the space of three or four of the terminal rows of spines, 

 is peculiar in having an abruptly recurved or hooked tip (PI. XIII, 

 fig. 6). Toward the ventral end of the anterior row the setse 

 become less curved, more slender and the terminal hook less abrupt. 



Posteriorly the setse of succeeding rows become much longer, 

 relatively more slender, and almost straight. A typical one is 

 •exhibited in PI. XIII, fig. 4. Such setse, which are very nvmier- 

 •ous, have the following characteristics : They are slender and taper 

 regularly from the thickest point in the proximal third to the acute 

 tip, which is slightly curved and sometimes suggests the hook of the 

 •dorsal setse by the faintest indication of a recurvature. The spinous 

 region is less extensive than on the dorsalmost seise, and the spines 

 are excessively fine, except toward the free end, where the else- 

 where very close long rows become broken up into short detached 

 plates, which alternate on Ihe opposite sides of the seta. Proxi- 

 mally they again become irregular. In some cases these spinous 

 rows actually encircle the setre, l)ut usually there are two intervals 

 on opposite margins, that on the concave side being occupied by a 



