204 PROCEEDINGS OF THE ACADEMY OF [Vol. LXXV 



curved, the two together bracket-shaped, nearly meeting at a 

 wide angle medially, the lateral ends bent or hooked anteriorly to 

 embrace the pad-like nuchal organs just mediad of which they 

 bear short series or groups of small eye-spots. When the ocular 

 folds are pigmented, as they often are, the eyes are obscure but 

 when they are unpigmented 8-10 of these eyes stand out conspicu- 

 ously on each ridge. Nuchal organs small, low, rounded, pad-like 

 elevations arising from a slight depression between the ocular 

 ridges and the ridges of the median plate. Tentacular lobe a thick, 

 crescentic or horse-shoe shaped, somewhat trilobate fold, with its 

 lateral ends tucked into the mouth. Tentacles about 40, arranged 

 in a narrow, crowded, transverse band or single irregular series, 

 varying in length, the longest equaling the prebranchial region, 

 slender, terete, slightly clavate toward tips. Mouth large, with a 

 thick internal lower lip inside the margin of the peristomium. 



Counting the region anterior to the paleoli as I and II (Fauvel), 

 these two segments are obviously divided by a very shallow annular 

 furrow into two rings of equal size dorsally, of which the first 

 or peristomium is about twice as long as II ventrally and projects 

 forward as a prominent, slightly crenulate, flattened lower lip. 

 Ventrally each of these segments is crossed by a narrow, raised, 

 transverse line, both somewhat glandular. 



The setigerous thoracic region (IV-XX) constitutes about | 

 of entire length, consisting of a broad, flat, ventral sole with promi- 

 nent lateral parapodial ridges which are somewhat rugous and 

 project beyond the sides of the very smooth arched dorsal region 

 Somite III is enlarged, about one-half as long as I and II ventrally, 

 bearing dorsally prominent paleolar tubercles which extend forward 

 and somewhat embrace II. Somites IV and V together about 

 equal III. The remaining thoracic segments gradually increase 

 in length and diminish in width until the last is about three -fiths 

 as long as wide. Ventrally the segments bear ventral glandular 

 plates, each marked by a slight transverse ridge, especially promi- 

 nent on III. On the pre-uncinial segments these ventral plates 

 reach high up to the setigerous tubercles and cover the entire 

 length of the segment, but from VII caudad they are confined 

 between the tori and gradually become shorter, until in the post- 

 erior thoracic region (beginning with XIII) they form only narrow 

 transverse bands across the anterior region of the segments. 

 Ventrally the segments are well defined by the ventral plates and 

 dorsally by shallow but distinct furrows which often disappear 

 posteriorly. Posterior thoracic segments pass gradually into the 

 abdominal, the last two often lacking all trace of ventral plates and 

 distinguishable from abdominal segments by the possession of setae 

 only. 



Abdomen regularly tapering caudad, the segments becoming 

 shorter as well as narrower, generally similar to thoracic segments, 



