298 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 7 



179), dredged from central and southern California (in 38 to 357 fms), 

 differs from the new species in the following : ( 1 ) it has a slender, erect 

 antenna near the truncated apex of the prostomium; (2) the dorsal trans- 

 verse membranes are ruffled; (3) there are lateral interparapodial 

 pouches after the fifteenth segment. The nature of the pygidium could 

 not be determined because of fragmentary specimens. 



Holotype.—AHF no. 32. 



Distribution. — Mission Bay, California, intertidal. 



Genus PRIONOSPIO Malmgren 

 Prionospio alata Moore 



Moore, 1923, pp. 185-186. 



A single specimen, agreeing with the original description, has been 

 dredged off La Jolla, in about 45 fms, during a cruise of the E. W. 

 Scripps of the Scripps Institution of Oceanography, April 19, 1938. 

 Moore's single type specimen was dredged off Point Pinos Light in 56-57 

 fms. 



Discussion on the Genera Boccardia Carazzi and 

 polydora bosc 



These 2 genera have long been separated on the basis of a single char- 

 acter — presence or absence of branchiae anterior to the modified segment. 

 The artificiality of this separation may be argued, especially since the 

 presence of branchiae on segments posterior to the modified one has only 

 specific significance. It is of interest that among the species of these genera, 

 some of each have 2 kinds of heavy spines in the modified segment. Thus, 

 among species of Boccardia, proboscidea has 2 kinds whereas uncata, 

 redeki, and truncate have but a single kind. Among species of Polydora, 

 tricuspa and citrona have 2 kinds; most of the others have but a single 

 kind. Furthermore, among the species of these genera, B. uncata, P. ha- 

 mata, and P. hoplura possess heavy hooks, greatly resembling one another, 

 in some posterior segments. These characters would seem to have phylo- 

 genetic significance. It is thus not convincing that the species comprising 

 these genera are clearly separable as are those of most other genera. How- 

 ever, their separation is here maintained for convenience. 



The modified segment is herein designated the fifth (setigerous) seg- 

 ment, although it is recognized that the peristomium (achaetous) is 

 actually a segment. Some authors have therefore called the modified one 

 the sixth. 



