NO. 13 POLYCHAETOUS ANNELIDS HARTMAN IJ 



Martin W. Johnson. Plankton tows were made from the end of a 

 1,000-foot pier, along the open ocean. Frequently these tows contained 

 larvae of a Polydora in which the modified hooks and hooded crotch- 

 ets are strikingly like those in the unique specimen from James Island 

 (cf. figs. 3, i and 3, d) . Also, these pelagic larvae had up to 19 

 setigerous segments, indicating a long pelagic life, and hence the pos- 

 sibility of being widely disseminated by ocean currents. In spite of 

 shore collecting in the vicinity of La Jolla, the adults were not recov- 

 ered. Subintertidal zones were not examined. 



These larvae are characterized as follows (based on living larvae) : 

 Each setigerous segment has a single black, irregular blotch over the 

 middle dorsum; the prostomium is broadly rounded anteriorly (fig. 

 3, c) ; there are 4 (more or less) eye spots ; the palpi are stout, short ; 

 ciliated paratrochs are present on segments VI (modified), VIII, XI, 

 XIV, and ciliated rings on the peristomium and anus. Parapodial 

 glands are visible in segments VIII to XII (fig. 3, c) ; the first seg- 

 ment ( = peristomium) has a few short ventral setae which are per- 

 haps lost later ; the second segment has both dorsal and ventral fas- 

 cicles, the ventral setae much the shorter, and not present in the adult 

 (fig. 3, k) ; hooded crotchets are present from segment VIII ; segment 

 VI has two kinds of stout modified hooks (fig. 3, /) identical with 

 those in the specimen from the Galapagos Islands and a slender 

 fascicle of 4 or 5 capillary setae (fig. 3, /). No branchiae are visible. 



Polydora tricuspa differs from other species of Polydora in that the 

 modified segment (VI) has 2 kinds of stout hooks, a falcate and a 

 tricuspid, in addition to a ventral fascicle of lanceolate setae. The 

 hooked crotchets are bifid ; branchiae are limited to 18 segments. 



Holotype. — U.S.N.M. no. 20428. 



Distribution. — Galapagos Islands; southern California. 



CIRRATULIDAE 

 CIRRATULUS NIGER, new name 

 Fig. 3, b 

 Cirratulus nigromaculata Treadwell, 1902, p. 204, not Grube, 1870, p. 504. 



Collection. — Station No. 8-38; 3 specimens. 



Length to 13 mm., widest at about the tenth setigerous segment. 

 General appearance dark, with pale tentacular cirri and white branchial 

 filaments. Head and anterior end as shown by Treadwell (1902, p. 

 204). Under high magnification the dark color resolves itself into 

 diffuse dusky patches, darkest over the middorsum in the anterior 



