1905.] NATURAL SCIENCES OF PHILADELPHIA. 539 



palpi are likewise slender and from 6 to 9 times (usually the former) the 

 length of the prostomium. They taper regularly to an acute tip and 

 are marked with longitudinal ciliated lines. The tentacular cirri are 

 similar in form to the median tentacle, but they are much more strongly 

 ciliated and only f as long. The mouth is bounded behind by a 

 strongly furrowed lip which reaches to III. In a specimen 30 mm. 

 long the proboscis is extended to a length of 9 mm. and a breadth of 

 3 mm. It is provided with acute jaws of the usual form and bears 9 

 soft papillse above and 9 below. 



The body is narrow and nearly linear; its ventral width scarcely 

 equals the extreme length of the parapodia, and is practically uniform 

 from somite V to the middle of the body, beyond which it tapers very 

 gently to the pygidium. A strongly marked neural groove runs for its 

 entire length. Nephridial tubercles are first evident on IX and are 

 nowhere much elongated. Dorsally the greatest width is from VIII 

 to XIX. There are 39 somites. 



The 15 pairs of elytra are borne on somites II, IV, "\^ VII. IX, XI, 

 XIII, XV, XVII, XIX, XXI, XXIIl, XXVI, XXIX and XXXII. 

 They are remarkably large, overlap broadly both antero-posteriorly 

 and medially, have a soft membranous texture and a weak attachment, 

 so that they are easily detached. The first is subcircular, the next 3 

 are broadly reniform, and those following, except the last, broadly 

 elliptical ; the last is broadly subovoidal with a straight inner margin. 

 To the naked e5^e the scales appear quite smooth, but a moderate mag- 

 nification shows the greater part of the surface covered with scattered 

 small, slightly curved, conical spines which become more numerous 

 toward the posterior margin where they are associated with a few slen- 

 der, clavate cilia. Cilia of various lengths occur also on the free margin 

 of the scales. It appears that in natiu'e the elytra are frequently lost 

 and replaced, and that when detached asymmetrically the remaining 

 one of the pair will increase in size and completely cover the back as 

 far as the bases of the dorsal cirri of the opposite side. Even when 

 both elytra of a pair are symmetrically developed they overlap so 

 broadly in the median line that less than half of their extent is exposed 

 when all are in place. 



As indicated above the parapodia are elongated and fully equal the 

 body width. The prominent and slender neuropodia are ol^liquely 

 truncate distally and have the dorsal angle prolonged anterior to the 

 setae into a slender aeicular process with a free filament equalling the 

 ventral cirrus in length. The notopodium is a low cylindrical process 

 arising rather anterior to the base of the neuropodium and bears the 

 35 



