774 J. H. ASHWOliTH. 



specitiien there are ouly eleven gill^; the first of wliicli is on 

 the niutli segment. It may therefore be said that it is usual 

 to find the first gill in these specimens on the eighth segment 

 as in A. assimilis. Dissections of two of the specimens 

 show that there are five pairs of nepliridia, multiple ocso- 

 ageal glands, and no pouches on the first diaphragm ; and 

 sections of the anterior end prove conclusively that there are 

 no o to cysts. All these points are so characteristic of 

 A. ciaparedii that there can be no doubt that the speci- 

 mens belong to this species. 



I am indebted to Dr. H. P. Johnson for two specimens of 

 Arenicola from Puget Sound, AV^ashington. In one of 

 these ^ there are thirteen pairs of gills, but in the other the 

 seventh segment bears a gill only on the right side, the first 

 left gill being on the following- segment. Dissections of the 

 specimens and sections of the anterior end of one of them 

 fully confirm the determination of their species made by Dr. 

 Johnson (1901, p. 421) ; they are undoubted A. ciaparedii. 



It is therefore highly probable that Elilers is in error in 

 recording A. assimilis from California. In the first place, 

 his determination of the species of the Californian specimens 

 rests solely upon a character which is very variable and 

 almost useless for distinguishing species ; secondly, a re- 

 examination of what are probably the very same specimens 

 proves them to be A. ciaparedii, and this species has been 

 recorded from another point on the west coast of the 

 United States. 



A revision of Ehlers' record of the distribution of A. assi- 

 milis therefore becomes necessary, and may be given as 

 follows : — Adult typical specimens of A. assimilis have been 

 recorded from several places in the extreme south of the 



' it, lb reiiiurkublc tliut of the seven speciiiieiis exainiucd from the west 

 coast of the United Slates this is tlie only one which possesses the full 

 number of gills. On the contrary, it is unusual to find any departure from the 

 normal nninljer in Neajiolitan s|)eciniensof A. ciaparedii ; out of thirty-nine 

 examined only two show a reduction in the number of trills ; in each case 

 there are ihirteen on the left side, but only twelve on the right. 



