HEKATEEOBRANCHUS SHEUBSOLII. 195 



not much, that the ciliated groove of the tentacles of most 

 Spionids is used in conveying food down to the mouth, the 

 cilia being continuous with those of the mouth opening, which 

 would make it the more probable that the tentacles were once 

 outgrowths of the side of the mouth. According to this view, 

 the name "palp" given to the most ventral pair of cephalic 

 tentacles of Haplobranchus by Dr. Bourne might be retained, 

 but extended so as to include the other tentacles as well. Dr. 

 Bourne in his paper regards these other tentacles as peristomial, 

 from a certain superficial resemblance they bore to the peristo- 

 mial tentacles of Nereis, and he tries to show that the cephalic 

 branchiae of the Serpulidse are peristomial; but, as Meyer has 

 shown, there is no evidence of fusion of ganglia in the Serpulidse 

 as there is in the Nereidee. When Dr. Bourne wrote his paper, 

 however, he was unaware of the existence of Manayunkia, which 

 was first described in the same year (1883), or he might have 

 been led to different conclusions with regard to what he has 

 called " peristomial tentacles." ^ 



They originate [sections of Polynoe (Harmothoe) areolata] just where 

 the prostomium joins the peristomial and buccal somites, although they 

 appear to have more connection with the prostomium than with the other 

 somites. Their nerve-supply appears to come from the supra-cesophageal 

 ganglion." Such a description would need but little modification to serve for 

 the tentacles of some of the Spionidse (e.g. Polydora antennata) and 

 Cirratulidse (e. g. Heter ocirrus froutifilis). Bourne does not mention a 

 contractile blindly-ending vessel in them, but there is this in Staurocepbalus. 

 The chief difference is the absence of cilia on the palps of Polyuoe. 



1 As regards the rest of Meyer's view, I should like to point out that in 

 Hekaterobranchus the lateral parts of the collar are evidently not formed 

 by the ventral cirri, since these are present quite independently as well 

 on the 1st segment. The collar appears to be a mere folding of the 

 ventral surface ; if anything it could only be the dorsal cirrus which assists in 

 forming it. I have especially looked for the " Wimper-organe " on the pro- 

 stomium, which Meyer mentions (p. 639) as a feature which we might expect 

 to find in the Spionidse, but have been unable to find any trace of them. I 

 may also mention in reply to Meyer's suggestion (vol. vii, p. 723) that there 

 are probably thoracic nephridia with a single external duct in Haplobranchus, 

 that in my sections of Haplobranchus I have been unable to find any trace of 

 such an arrangement ; and I even doubt whether what Bourne marks " gl " in 

 bis figure of Haplobranchus are to be regarded as nephridia at all. There is 



