214 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL.7 



Stauronereis cerasina (Ehlers) 

 Plate 34, Figs. 38-41 



Staurocephalus cerasinus Ehlers, 1901, pp. 263-264. 

 Stauronereis cerasina Ehlers, 1901, pp. 147-149, pi. 19, figs. 11-17, pi. 20, 

 figs. 1-3. 



Collections.— A9^-36, 662-37, 683-37, 728-37. 8 specimens. 



Length 15 to 20 mm. Dorsal cirrophores are long, provided with slen- 

 der acicula, and the cirrostyles greatly surpass the neuropodia in length 

 (pi. 34, figs. 38, 39). Supraacicular setae are slender, lanceolate, serrated 

 along the cutting edge (pi. 34, fig. 41 ). Subacicular falcigerous setae have 

 a well-developed subterminal tooth, and the shaft is pilose distally save 

 for the smooth blunt tip (pi. 34, fig. 40). The prostomium has 4 dark, 

 reddish-brown eyes, the anterior pair being much the larger. 



Distribution. — Juan Fernandez, off southwestern South America; 

 Gulf of California, Mexico. Sublittoral, to 15 fms. 



Stauronereis gracilis Hartman 



Stauronereis gracilis Hartman, 1938, pp. 100-101, figs. 36-38. 

 Collection. — 905-38. 3 specimens. 

 Distribution. — California. Intertidal. 



Family Nereidae 



Separation of the Nereidae into genera has long been based, in part, on 

 the disposition of the paragnaths on the proboscidial rings, as also the 

 shape and structure of these parts (Kinberg, 1866, p. 170; Grube, 1873, 

 p. 56; and others). Thus, presence or absence of conical paragnaths on one 

 or both rings has separated such genera as Nereis, Ceratonereis, Eunereis, 

 and Leptonereis. Admittedly, however, the number of paragnaths on both 

 rings may vary from abundance to rarity between different species, and 

 even differs within certain limits in the individuals in a species. This char- 

 acter, therefore, is to be observed with caution and, if possible, correlated 

 with the nature of other parts. 



The genera that are sometimes included in Nereis Linnaeus include 

 Neanthes Kinberg, Ceratonereis Kinberg, Eunereis Malmgren, and Ne- 

 reis s. str. If the species of these genera and those of Leptonereis Kinberg 

 were to be arranged in a continuous series based on the number of conical 

 paragnaths on the proboscis, the limitation of genera would disappear. If, 



