152, “WILLIAM BLAXLAND BENHAM. 
to the anus. It has the dorsal flexure found in the trocho- 
phere, the cesophagus passing dorsally from the mouth. 
During development the prostomium dwindles considerably 
and the ciliated band disappears, but these do not appear to 
be actually eaten as in Actinotrocha, nor is any (?) remnant 
of prostomium left in the adult Sipunculus. 
Conclusion.—If we weigh these resemblances and dif- 
ferences between Phoronis and Polyzoa or Sipunculids, more 
especially in the larval stage, I believe that the resemblances 
will justify us in placing Phoronis in nearer relation to 
the Sipunculids than to the Polyzoa. 
List oF Papers REFERRED TO. 
1. Antwan, JAmes.—‘ Monograph of Freshwater Polyzoa,’ Ray Soc., 
1856, p. 55. 
2. Barrots, J.—‘ Mém. sur la metamorp. des Bryozoaires,” ‘Ann. Sci. 
Nat.,’ 6th ser., ix, 1879; “Metamorph. de quelques Bryozoaires,” 
‘Ann. Sci. Nat.,’ 7th ser., i, 1886-87; and other memoirs. 
3. vAN Benepen, P. J.—“ Notice sur un annelid cephalobranch sans soies,”’ 
‘Ann. Sci. Nat.,’ 4th ser., x, 1858, p. 11. 
4, CatpwetL, W. H.—* Preliminary Note on the Structure and Develop- 
ment of Phoronis,”’ ‘ Proc. Roy. Soc.,’ xxxiv, 1883, pp. 871—883. 
5. CatpwetL, W. H.—* Blastopore, Mesoderm, and Segmentation,” 
‘Quart. Journ. Mier. Sci.,’ 1885, pp. 15—26. 
6. DystEeR, F. D—*“ Notes on Phoronis hippocrepia,” ‘ Trans. Linn. 
Soc.,’ xxii, 1858, p. 251. 
7, Farre, A.—“On the Structure of the Ciliobranchiate Polypi,” ‘ Phil. 
Trans.,’ 1837, p. 408. | 
8. Harmer, S. F.—‘“Structure and Development of Loxosoma,” AUD 
Journ. Mier. Sci.,’ 1885, pp. 261—328. 
9. Harmer, 8S. F.—“ Life-History of Pedicellina,’ ‘Quart. Journ. Micr. 
Sci.,’ 1856, pp. 239—261. 
10. Harmer, S. F.—“Sur l’embryogenie des Bryozoaires Hctoproctes,” 
‘Arch. de Zool. Exp. et Gén.,’ 2nd ser., v, 1887. 
11. Harmer, S. F.—(In Appendix to McIntosh’s “Cephalodiscus dode- 
calophus”) ‘“ Challenger” Reports,’ xx, 1887. 
