472 PROCEEDINGS OF THE ACADEMY OF [June, 



or less freely produced at the sides and the latter 2 partly coalesced 

 \'entrally ; no dorsal papillae. Ventral plates 10, on somites V to XIV, 

 the first 9 narrow parallelograms, the last broadly eiUptical and some- 

 what separated from the others. Anus large, terminal, its margin 

 faintly wrinkled. 



Branchise 3 pairs, on II, III, and IV, much branched, the number of 

 divisions about equal on all, but somewhat shorter posteriorly. They 

 have very nearly the form of the brancliise of A . johnstoni i\Igrn., and 

 consist of a more or less bent and twisted main stem from which the 

 filaments arise at intervals and divide dichotomously once, twice, or, 

 rarely, even 3 times, or a few remain simple; the basal branches are 

 long and slender, but the length gradually decreases until the apical 

 ones are very short. 



On the thoracic segments the parapodia are represented by rather 

 broad ridges, the setigerous tubercle being merely a more prominent 

 projection at its dorsal end slightly caudad of the line of the uncini. 

 The second uncigerous torus is the longest, but the decrease in size is 

 very slight to the last thoracic segment and is accompanied bj^ a slight 

 ventral shifting. The abdominal parapodia are rather large, fleshy 

 and strongly bent, and bear a striking resemblance to the so-called 

 false feet of a lepidopterous caterpillar, but posteriorly become more 

 slender and sloping, and finally diminished in size; all are situated on 

 the ventro-lateral angles of the body. 



Capillary setae occur on IV to XX inclusive, uncini from V to the 

 pre-anal somite inclusive. The former have a narrow blade, nowhere 

 exceeding ^ the diameter of the shaft, the blade fringed for about ^ its 

 length, and a delicate smooth tip. The uncini are arranged in inter- 

 locking double rows of about 170 (XX) on the thoracic somites from 

 XI to XX; on all others in a simple series directed forward; on each 

 parapodium of somite XXX there are 80. Their bases are short with 

 the internal margin strongly convex, the anterior end rounded, the pos- 

 terior pointed, and a prominent subtostral process; the rostrum long, 

 very acute, and strongly hooked, the sinus narrow, vertex much ele- 

 vated with a prominent crest of at least five transverse rows of spines, 

 of which the first contains 5 or 6 large ones and the last 8 to 10 small 

 ones. The abdominal uncini are much smaller, with relatively shorter 

 bases, the neck narrower and the crest higher, with more numerous 

 rows of spines. The uncini are nearly colorless, the capillary setae 

 glistening yellow. 



North of Sendai Bay, 3,768, 25 fms., type and one other specimen 

 with portions of a thick mud tube. 



