1910.] ' NATURAL SCIENCES OF PHILADELPHIA. 395 



to become longer and more curved anteriorly, while posteriorly many 

 of those in the middle part of the main series become imperfectly 

 coalesced with the shafts to form simple seta?. Peristomial setffi are 

 •all of the notopodial-capillary type but the hairs are reduced to the 

 finest denticulations. 



Station unknown. Labeled "with yellow Doris" probably indi- 

 cating a commensal habit. 



In general aspect this species somewhat resembles Sthenelais fusca 

 Johnson but differs greatly in the character of the setae. Indeed, the 

 character of the seta3 is so unique that I feel compelled to separate 

 this species from typical Sthenelais, having a complex group of neuro- 

 podial setae most of which have distinct articulated appendages, as the 

 type of a distinct genus or subgenus Sthenelanella. 

 Sthenelais tertiaglabra sp. nov. PI. XXXIII, figs. 113-120. 



Based on two short anterior ends: a cotype consisting of 36 segments 

 from a slightly larger specimen and the type of 45 segments, measuring 

 22 mm. long, with a maximum body width of 1.3 mm., 2.5 mm. between 

 tips of parapodia and 3.1 mm. between tips of setae; depth about 1 mm. 

 Prostomium (PI. XXXIII, fig. 113) subcircular, somewhat wider than 

 long, with the sides bulging slightly toward the anterior end, slightly nar- 

 rowed behind and bearing a low protruberance on each side. Eyes two 

 pairs, black; the dorsal larger, situated behind base of middle tentacle, 

 separated by one-fourth or more width of prostomium; ventral pair 

 on frontal face immediately beneath tentacular lamella?, smaller and 

 somewhat closer together than dorsal pair. Median tentacle arising 

 between the four eyes by a stout ceratophore about three-fourths as 

 long as prostomium; style moderately slender, regularly tapered to a 

 short faintly articulated filament terminating in a minute knob, the 

 cuticle unequally thickened and peculiarly crenulated or crmkled but 

 lacking sensory cilia. Antennal lamella? spoon-shaped, ovate, diverg- 

 ing wing-like from each side of base of ceratophore and nearly as long. 

 Lateral tentacles coalesced with dorso-medial face of peristomial 

 parapodia, the short free tip projecting beyond the end of the parapo- 

 dium to a distance of about one-half the length of the latter with the 

 end knobbed and slightly articulated. Like the median tentacles 

 these lack large sensory cilia but are provided with minute tactile 

 organs visible under high magnification. Palpi slender and delicate, 

 about five and one-half times length of prostomium, regularly tapered 

 and smooth. A very slight facial ridge runs to the mouth. 



i^rostomium completely concealed beneath prostomium, its parapodia 

 produced straight forward at sides of prostomium and reaching about 



