192 PROCEEDINGS OF THE ACADEMY OF [Vol. LXXV 



segments are about as long as wide and separated by clearly 

 defined furrows. The dorsal two-thirds of the thoracic segments 

 takes the form of a perfectly smooth continuous arch, the ventral 

 one-third of a pair of broad, prominent, muscular, parapodial 

 ridges which are separated by the ventral plates anteriorly and by 

 the neural groove posteriorly, the latter continuing on to the 

 abdomen. The last abdominal segment is similar to the others 

 and may not be the true pygidium but a regenerated ring. 



Anterior ventral plates are thick, ill-defined, glandular areas 

 filling the entire space between the parapoclia. They begin to be 

 differentiated at VII, and those on VIII to XI are distinct, broadly 

 elliptical areas, the last (on XII) being very small and divided 

 into halves by a median groove. 



Parapodia begin as prominences on the side of II and for several 

 segments form a continuous ridge not clearly defined from the 

 ventral plates. With the differentiation of the ventral plates, the 

 parapodia also become distinct and form short, thick, prominent 

 tori in the thoracic region never exceeding a length of I or | the 

 circumference of the body. On III, there is a minute cirrus just 

 above each parapodium; none is evident on other segments. 

 Abdominal parapodia are small, prominent, backward projections 

 from the caudo-ventral -lateral region of the somites. The first 

 two segments (XIX and XX), which lack setffi, have tori of a 

 transitional type and may be expected to bear setre in some speci- 

 mens. 



Small compact setae tufts arise from the dorsal ends of the para- 

 podia on fifteen segments (IV to XVIII) and curve strongly 

 dorsad. The setae are rather long, slender, strongly curved and 

 have a narrow wing and very delicate flattened tips. Uncini 

 (Plate XVII, fig. 8) begin on V and form single series to X, double 

 series for the remainder of the thorax. Number of uncini always 

 small, 46 on VII, about 36 on each row of X, about 40 on each row 

 of XVIII. They have a small body with narrower base than those 

 of L. imda; large head with strongly hooked beak and large, high 

 crest, consisting of about six rows of from six to ten spines and very 

 obscure guard. Abdominal uncini are in a single series (32 on 

 XXV) and are similar to the thoracic but smaller and more delicate. 



A small portion of tube is formed of fine mud and is very fragile. 

 Type only known. Station 4526, off Point Pinos Lighthouse, 

 204-239 fathoms, soft gray mud. 



Polymnia nesidensis v. Marenzeller subsp. japonica Moore. 



A single example appears to be of this form, hitherto known only 

 from Japanese waters. It differs from the European P. congruens 

 V. Marenzeller, in the strictly dichotomous branching of the gills. 

 Gills three pairs, differing much in size; those of the first pair 

 largest, with tall erect stems branched dichotomously eight or nine 



