iOlO.] ' NATURAL SCIENCES OF PHILADELPHIA. 379 



Neuropodial setae mostly concealed above by the felt, arranged 

 in the usual three series, the dorsal being stout and deep brown and 

 two or sometimes three in number, the middle paler, about half as 

 thick and four or five, the ventral yellowish l)row^n and much more 

 slender and more numerous, ten being almost invariably present 

 on middle segments. As compared Avith most similar species setse of 

 all three seiies are long and slender and shaped moi-e nearly like these 

 of ^4. hamcita than any other species. All are nearly straight — those 

 of the ventral series (Pi. XXXII, fig. 81c) most ciu'ved — perfectly smooth 

 with no trace of hairyness or tuberculation and with a slight subtei- 

 minal enlargement tapering to a .slender acuminate tip, the last two 

 characters also much more accentuated on the ventral seta; (figs. 81a-r)_ 



Notopodium bearing two series of large seta; (Pi. XXXII, figs. 79 and 

 80) the ventralmost or lateral arranged in a nearly vertical series of 

 six to eight which pass through the felt and then l)end sharply dorsad 

 with theii- slender ends resting \ipon it. The dorsalmost group is 

 irregular and usually consists of six to eight seta more or less dis- 

 tinctly in two short rows which penetrate the felt obliquely and rest 

 upon it more or less concealed in the co\'ering silt. All of these setfe 

 are dull brown, soft of texture, longitudinally striated, quite without 

 surface asperities, stout and flat at the base and tapered to slender 

 ends with h<^oked tips. The apical sheaths sometimes present are 

 unusually long and are free of hairyness (fig. 80). Seta of the ventral 

 series are shorter and more abruptly tapered, the dorsal more genth' 

 tapered and reaching beyond the middle of the body, inci-easing in 

 length from before backwai'd. The capillary fibers have the usual 

 arrangement into dorsal, intermediate and ventral tufts. The foi-mer 

 are confined to elytrophorous segments and are very al>undant, forming, 

 with the intermediate tuft, the dorsal felt, the individual fibers being 

 very long and slender with hooked tips. The ventral tuft forms the 

 iridescent plumes and the fibers are short, coar.sei', somewhat rigid, 

 tapered to very fine straight poijits and are veiy smootli so tlial no 

 foreign matter adheres to them. 



Toward the head the arrangement of tlio nolopodial seta^ becomes 

 simplified by the merging of the two groups of notopodial setse and 

 two groups of fibers. Neuropodial setio become longer and more slender 

 and on III and II. the ventral series is replaced ])y a dense patch of deli- 

 cate bipinnate setae (PI. XXXII, fig. 82). In this group the dorsalmo.st 

 setae are longest and coarsest and bear a short pennant-like tip. Pass- 

 ing toward the ventral side this tip increases in size at the expense of 

 the remainder of the setse and becomes spirally turned until on the 



