8 IOWA STUDIES IN NATURAL HISTORY 
The slender median tentacle is inserted in a dorsal groove which extends 
backward for more than one-half the length of the prostomium. On 
either side the prostomium is prolonged into a stalk, each stalk with a 
large eye at the end. A second, much smaller eye on either side lies a 
little in front of the middle of the prostomium. The lateral tentacles 
lie one beneath each eye-stalk and are approximately the same form and 
size as the median. The palps are fully ten times as long as the ten- 
tacles, each tapering to an acute point from a base which is one-half as 
wide as the prostomium. Scattered irregularly over the surface of the 
palps and much more thickly crowded together toward the apices are a 
large number of spiny processes most of which are irregularly conical in 
outline and an occasional one may be bifid. Figure 11 is a camera draw- 
ing of the profile of a palp taken near the apex. In addition to being 
more closely crowded together those toward the apices are larger than 
those found elsewhere. 
Somite 1 (figure 10) is only a very little broader than the prostomium 
and its tentacular cirri closely resemble in form and size the antennae, 
though they are a trifle greater in diameter. The cirrophores of the ten- 
tacular cirri extend forward on either side to the level of the posterior 
margin of the anterior eyes. 
The parapodia of the anterior somites (figure 12 is drawn from the 
19th) have a heavy, obliquely truncated setal lobe with equal anterior 
and posterior lips. In the interior is a long rod of a brown chitin which 
extends into the interior of the body and has nothing to do with either 
the sete or the acicula. A similar structure occurs in Panthalis oculata 
Treadwell (Treadwell 1901, pages 188, 189, figure 15). The dorsal cirrus 
has a heavy cirrophore and is itself thin-walled and conical, extending 
only a short distance beyond the setal lobe. The ventral cirrus is smaller 
than the dorsal but similar to it in outline. There is a single very heavy 
acicula. Beginning with somite 10 each parapodium has on its dorsal 
surface a series of thin-walled globular pustules. In somites with elytra 
the largest lie lateral to the elytrophore, though smaller ones may occur 
as far toward the dorsal surface as the base of the elytrophore. In other 
somites they are scattered irregularly over the surface of the parapodium 
(figure 12). From about the 50th somite backward these become more 
prominent, assume a cylindrical form with rounded ends and in the pre- 
served material are decidedly an opaque white in color. Through a large 
part of the posterior region they have a regular arrangement. In the 
elytra-bearing somites there are two, lateral to the elytrophore on the 
dorsal surface of the parapodium. In the other somites there are also 
two, one on either side of the dorsal cirrus, lying, that is, one on the side 
toward the apex of the parapodium and the other toward the dorsal 
median line. 
The very heavy acicula does not protrude from the surface of the 
parapodium. Dorsal to it in anterior somites is a row of slender color- 
less sete which suddenly narrow toward the apex and carry along the 
narrowed portion a row of slender fine hair-like processes. (Figure 13) 
