192 FLORENCE BUCHANAN. 



glena; and, finally, both primary and secondary rays multi- 

 plying greatly until we get the complex condition of other 

 Serpulids (tribes Sabellidse, Serpulidse proper, and Eriogra- 

 phidse) ; and in all these forms, even in the most elaborate, 

 the same structures can be traced. 



In Haplobranohus and Manayunkia there is a single pair 

 of tentacles, with the same single blindly-ending contractile 

 vessel running up them as in Hekaterobranchus and other 

 Spionids.i The other tentacles, which I would regard as 

 multiplications of this one, have not as yet the contractile 

 vessel developed in them ; but their cavity is, as I have been 

 able to ascertain from sections of Haplobranchus, in continuity 

 with that of the tentacle containing the blood-vessel some way 

 above the base. 



In Amphiglena and Fabricia all the branchial rays, and 

 not a single pair only, have the contractile vessel in them. 

 That they also still retain their tactile function is shown 

 by the fact that each ray is non-ciliated, but provided with 

 short, stiff, tactile hairs at its apex. In all the other Serpulids 

 there is the same single contractile vessel ending blindly in 

 each secondary ray.- 



' Bourne calls these " palps " in Haplobranchus, but says their homology 

 is difficult to determine. They are certainly, as confirmed by sections, ventral 

 in position. Leidy says that they are dorsal in position in Manayunkia, but 

 apparently this has not been confirmed by sections. If there is this difference 

 in position in what would at first sight (cf. the figures of Bourne and Leidy) 

 appear so very evidently to be the same thing, it seems to me that it would 

 go far towards showing that all the tentacles on the head of either form are 

 developments (multiplications) of one, it being indifferent in which one the 

 original characteristic contractile vessel develops. 



^ It will be seen from the above that if I accept Meyer's premises, I do 

 not agree with him in his conclusions with regard to the relationships of the 

 Serpulidse inter se. That is to say, I do not regard the tribe Amphicoridse, 

 to which Haplobranchus, Manayunkia, Fabricia, and Amphiglena belong, as 

 degenerate from higher existing tribes, bat ratlier as primitive; i.e. I regard 

 these forms as the descendants (degenerate undoubtedly in many ways) of a 

 form more primitive than the ancestors of any of the other existing tribes. 

 No doubt, as Meyer remarks, they once led a much more sedentary life than 

 they now do ; but it does not therefore necessarily follow that they are 



