Gady Marine Laboratory^ St. Andrews. 35 



But oue of the most interesting Nereids iu this connexion 

 is the Japanese " Palolo " [Ceratocephale osawai), as recently 

 described and figured in a notewortby paper by Mr. Akira 

 Izuka *, Assistant Profes.-or of Zoology in the Imperial Uni- 

 versity, Tokyo. The species is much used by the Japanese 

 fishermen as bait, and occurs abundantly in the littoral region, 

 as well as extends into estuaries, tributaries, canals, and 

 ditches — burrowing iu mud to the depth of a foot or more, 

 like Nereis diversicolor of our own shores. The species thus 

 approaches the fresh- and brackish-water Nereids from the 

 Pacific coast and Hawaii, as recently described by Mr. H. 

 Parlin Johnson f, and extends the list of such forms, which 

 includes Sabellids and others. 



The Japanese " Palolo," which has a dark brownish colour, 

 leaves its burrows in the mud with the flood-tide and creeps 

 about in search of food. It reaches the length of 200- 

 250 mm and is 4 mm. in breadth, and may have as many as 

 300 segments. In this condition it resembles the ordinary 

 type. Early in September, however, the change to the epi- 

 tokous form takes place, and the sexes differ in colour, the 

 male being more dusky (brownish) than the female, which is 

 for the most p irt bright red. The body in both sexes con- 

 siderably increases in breadth. Then the posterior region, 

 comprising about two thirds of the total number of segments, 

 begins to be differentiated — being narrower than the anterior 

 region and of a ditlereut colour, dull brownish with a pale 

 streak in the middle. Specimens in this condition are found 

 by digging in the mud about a week before swarming — just 

 as ^Ir. Woodworth procured his in the coral-blocks. The 

 narrowed posterior region, however, is not utilized for the 

 spreading of the eggs or spermatozoa, but degenerates and is 

 cast ofi', apparently in many cases even before swarming, 

 though a few are found swimming with the slirivellcd poste- 

 rior end attached. Shortly after the change just alluded to, 

 the annelids leave their burrows and become pelagic — swarm- 

 ing near the surface of the water to a depth of several feet, 

 and discharging ova and sperms from the aperture at the end 

 of the anteri(jr region (where tlie separation of the shrivelled 

 posterior region took place). Tiiey are captured at night in 

 great numbers by boats provided with a light, which attracts 

 the annelids, and various nets, and they are much esteemed 

 as bait. The swarming annelids appear to be carried by the 

 tide seawards, tliough many perish previously by rupture of 

 the body-wall or ottierwise. 



* Journ. Coll. Sc. Imp. Univ. Tokyo, Ja] an, vol. xvii. ii. p. 1, pi. i. 

 t Mark Anniversary Volume, art. x. p. 2Uo, pl.s. xvi. & xvii. (190 1). 



3* 



