724 PROCEEDINGS OF THE ACADEMY OF [NoV., 



broad, fiat, smooth dorsal lobe projecting prominently over the mouth, 

 and much shorter thin lobes on each side which meet in the middle 

 line below and join the peristomium by a narrow isthmus. Tentacles 

 numerous but small, borne on rather restricted areas which meet in the 

 middle line and extend on each side of the posterior part of the prosto- 

 mium. In the preserved specimen the length of the tentacles is less 

 than the diameter of the branchial region. They are attached by 

 contracted bases in the same manner as Andrews has described for 

 L. turgida. There is no post-tentacular fold and no eyes. 



The peristomium is largely retracted within the free margin of the 

 first ventral plate, from which it projects as a pair of thin lobes which 

 widen dorsally and conceal the ventral limb of the prostomium ; on the 

 dorsal side the peristomium is scarcely recognizable. 



Three pairs of branchiae occur on somites II, III and IV; the first 

 is very large, with a length exceeding the diameter of the body at that 

 point, while the third is scarcely one-fifth as long. They are tall 

 arboriform, each with a stout, tapering, irregularly bent stem bearing 

 irregularly alternate branches (5 on the 3d to 11 on the 1st), each 

 of which again divides in the same irregular manner 3 or 4 times, 

 resulting in very numerous, fine and densely tufted terminal twigs. 



The first parapodium is merely a setigerous tubercle just beneath the 

 third branchia. The remaining thoracic ones have rather prominent 

 dorsal setigerous tubercles and uncigerous tori which are at first short, 

 but increase in length and shift ventrad as the ventral plates diminish 

 in size ; posterior to the region of the ventral plates these tori become 

 more elevated and nearly meet in the ventral mid-line. The abdomi- 

 nal uncigerous tori are truncate, flattened tubercles projecting caudad 

 from the posterior margin of the somites on the ventro-lateral angle ^ 

 the caudal members of the series becoming minute. 



The setae (fig. 11) of each tuft are arrranged in two vertical rows, 

 one composed of more slender, the other of stouter set®. The former 

 are nearly colorless, slightly curved, axially faintly striated and have 

 a very narrow marginal wing. The latter are yellowish, nearly 

 straight, rapidly tapering in the exposed part, doubly winged, both 

 wings being obliquely striated and one much wider, the core strongly 

 marked with parallel longitudinal striations and the superficial fibers 

 radiating in all directions to the surface which, as a consequence, has 

 the appearance of being regularly marked with rows of fine granules 

 or very short lines. 



On somites XI to XX the uncini are in two rows, on V to X inclusive 

 and caudad of XX in but one row. On the posterior thoracic somites 



