1923] NATURAL SCIENCES OF PHILADELPHIA 189 



versely across the prostomium in front of the ej^es and two similar 

 lines parallel and very close together behind the eyes, along what 

 is apparently the pro-peristomial boundary. 



Representing the peristomium is an annulus, narrow dorsally 

 and expanded ventrally to reach forward nearly as far as the 

 anterior end of the prostomium. It forms prominent, much fur- 

 rowed, pouting lips, surrounding the large antero-postcriorly elon- 

 gated mouth, in front of which is a pair of transverse, compressed 

 cushion-like elevations probaljly representing the i)alps. Immedia- 

 tely dorsal to these, below the eyes and separated from each other 

 by the anterior frontal ridge only, are the large, prehensile tentacles, 

 which are thick and transversely grooved at the base and in the 

 contracted state, in which they exist in this specimen, reach to 

 somite XXV. These tentacles are similar to those of the Spionidae 

 and apparently belong to the peristomium, though v. ]\Iarenzeller 

 and some others consider them to be prostomial. 



The metastomial region is somewhat depressed, with the venter 

 flattened and the dorsum regularly arched, but posteriorly it becomes 

 nearly terete. It increases in width to a])out XXX and then 

 gently narrows to the caudal end which is terminated by a short 

 dome-shaped pygidium with a vertical slit-like aiuis. Except for 

 the first two, which are coalesced ventrally, the somites are well 

 defined by sharp furrows. The first is very short, the second, 

 equally short ventrally, but much longer dorsally. Succeeding 

 ones become gradually longer until by XXXV, they are about 

 one-half as long as wide, which is about the proportion maintained 

 for the rest of the length. The anterior twenty are somewhat 

 contracted and marked by cross-furrows which divide them more 

 or less irregularl}^ into three or four secondary annuli. In the 

 middle and posterior region these furrows disappear and the sur- 

 face becomes smooth. 



Beginning at the furrow II/III and continuing to XXIII/XXIV, 

 are very obvious, though small, intersegmental ])ores in the median 

 dorsal line. Caudad of that point they can no longer be detected. 



Four pairs of stout, round, smooth, slightly tapered notocirri or 

 gills are borne on the first four metastomial segments (II-\'). 

 At the base they are about as thick as the cephalic tentacles and 

 equal in length the anterior 18 to 22 segments. All arise near the 

 dorsalmost level of their segments, but the first and last are most 

 ventral, the second slightly higher and the thirtl still higher. 

 Below the second is a small achaetous tubercle not present in 

 relation with any of the others. 



Somites I to IV are achsetous (Plato XVII, figs. 3, 4), V bears a 

 setigerous neuropodial tubercle and all of the others both neuropodia 

 and notopodia bearing seta. All parapodia are simple ventro- 

 lateral elevations, each divided by a slight depression into a small 

 neuropodial and notopodial papilla of which the former is most 



