276 J. T. CUNNINGHAM. 



the subject, at present I can only say that the evidence 

 adduced in favour of their specifically nervous nature is quite 

 inadequate, and that the possibility of a phylogenetic connec- 

 tion between these neural canals in the Chsetopoda and the 

 notochord of the Chordata, cannot at present be altogether 

 dismissed. 



In concluding this paper I have to explain that my attention 

 was attracted to the points discussed in the course of a 

 systematic examination of the Polychseta, which I carried on 

 at the Granton Marine Station, in collaboration with my friend 

 Mr. G. A. Ramage, Vans Dunlop Scholar in Edinburgh 

 University. 



For the facts and views I have set forth I am alone respon- 

 sible, but the collection and identification of specimens were 

 chiefly carried on by Mr. Ramage, and he rendered much 

 valuable assistance in preparation and dissection. The draw- 

 ings for the paper were all executed by myself. 



EXPLANATION OF PLATES XVII, XVIII, and XIX. 



Illustrating J. T. Cunningham's paper "On Some Points in 

 the Anatomy of Polychseta." 



Fig. 1. — An entire nepbridium of Arenicola marina, seen under a low 

 power, in the fresh state. The membranous funnel has been turned back, so 

 that the ventral side is seen. A. Anterior, P. Posterior end. bl. Blood- 

 vessel, whicli joins the branchial vein. d. b. Dorsal fringed border of nephro- 

 stome. ne. Nephrostome. go. Gonad. 



Fig. 2. — Optical section of a portion of the wall of the nepbridium of 

 Arenicola, after treatment with osmic acid. bl. Blood-vessel. E, Zeiss, oc. 3. 



Fjg. 3 t — Horizontal section of 2nd and 3rd and part of 1st somites of 

 Cirratulus cirratus. ne. Nephrostome of anterior nepbridium, opening 

 from buccal somite, a.n. Ascending part of the nephridium. d. n. Descend- 

 ing part. se. Transverse and longitudinal septa. A, Zeiss, oc. 2. 



