1902.] NATURAL SCIENCES OF PHILADELPHIA. 261 



to tlie posterior end. They are short and directed dorsad. Anal 

 cirri, one pair, similar to dorsal cirri, but more slender. 



In the typical parapodium (PI. XIII, fig. 1) the neuropodium and 

 notopodium are distinctly separated ; the former is much the Uirger 

 and angular in outline, whereas the latter is rounded. Both termi- 

 nate in acicular lobes, of which the neuropodial is the longer. The 

 acicula are remarkable for the unusual length of the free, project- 

 ing end, which in the case of the neuropodial equals one-third of 

 the length of the longest setae, and is slender and curved. 



The dorsal cirri spring from conspicuous cylindrical bases. They 

 are larger than the median tentacle, with less of a subterminal 

 enlargement and shorter filamentous tip. The numerous cilia are 

 of two kinds ; the largest have a length of two to three times the 

 diameter of the cirrus, have a uniform diameter and are confined 

 to the distal half, excluding the filamentous tip which bears no 

 cilia ; the smaller ones are enlarged at the end and are more widely 

 distributed proximally. The ventral cirri are about one-fourth of 

 the length of the dorsal, slender, awl-shaped, and bear a very few 

 short clavate cilia. 



The first elytra are circular and fixed nearly at the middle ; the 

 next succeeding ones ovoid, with a slight anterior emargination at 

 the point of contact with the preceding peduncle; at the middle of 

 the body they are reniform, while posteriorly they again approach 

 the circular form. They are loosely attached and easily displaced 

 and are of a soft membranous texture, with very hard horny 

 spines (PI. XIII, fig. 2). Around the entire uncovered margin is 

 a fringe of rather widely separated cilia which become elongated 

 externally. With the exception of a small autero-internal margin 

 the entire surface is spinose, the spines as usual increasing in size 

 and complexity and decreasing in number from the anterior and 

 internal toward the posterior and external border. The first are 

 merely low cones. They .are succeeded by others with bifid sum- 

 mits which soon become larger. Passing obliquely across the middle 

 of the scale in its longest direction is a broad band of prominent 

 bifid spines, the apices of many of which are again divided. Most 

 of the spines on the posterior half have, on the other hand, a quite 

 distinct character. Here they are more remotely distributed and 

 are mostly trifid, with broad bases and each limb usually bifid at the 

 tip. Numerous otlier forms occur. Rome have a central spine aris- 



