REPORT ON THE TUNTCATA OF PLYMOUTH. 67 



Fig. 3. — Fyenoclavella attrilucens, gen. et sp. nov. The free portion of a zooid from a 

 colony growing on the stem of a Delesseria. Drawn from life, enlarged. 



Fig-. 4. — Perophora Listeri, Wiegmaun. Portion of the branchial sac. Zeiss, A, Oc. 2, 

 Cam. luc. 



A.»j. = Rudimentary horizontal membranes, 

 jt?. = Interserial papillae (= I'udimentary connecting ducts). 



Fig. 5. — Perophora Listeri, Wiegmann. Dorsal wall of pharynx, showing dorsal lamina 

 and aperture of hypoyangliouic gland, seen from inside. Zeiss, A, Oc. 2, Cam. luc. 

 ^.^. = Peiicoronal groove. 



e.v. = Ciliated vesicle, opening on the surface of a shield-shaped pad. 

 ^. = Ganglionic mass, 

 d.^. = Longitudinal membrane of dorsal lamina. 

 ?. = Marginal languettes. 

 Ti.m. = Rudimentary horizontal membranes. 



Fig. 6. — Perophora Listeri, Wiegmann. Dorsal lamina of another individual, seen 

 from the right side. Zeiss, A, Oc. 2, Cam. luc. 



Z. = Marginal languettes, interserial in position. 

 i.^. = Small marginal projections intermediate between the languettes. 



Fig. 7. — Diazona violacea, Savigny. Portion of branchial sac, seen from inside. Mag- 

 nified, slightly diagrammatic. 



A.w, = Horizontal membranes. 

 i.?.5. = Internal longitudinal bars. 



p. = PapillaB of the connecting ducts. (See Postscript.) 



Fig. 8. — Diazona violacea, Savigny. Six dorsal languettes. Zeiss, A, Oc. 2, Cam. luc. 

 A.m. = Horizontal membranes. 



Postscript. — By Professor Herdman's kindness I have recently been enabled to consult 

 Lahille's important Becherches sur les Tuniciers. Lahille points out that the appearance 

 of papillse on the internal longitudinal bars of the branchial sac of Diazona violacea, as 

 previously described by Savigny and Delia Valle, is a false one, produced by the thickened 

 remains of the " primitive branchial languettes." I had myself, like Aldei-, failed to find 

 any such vertical papillae as were represented by Savigny for this species, and was struck 

 by their apparently recumbent position in mounted preparations (see fig. 7) j but a re- 

 examination by means of dissecting needles has convinced me that Lahille is quite correct 

 in denying their existence altogether. The necessary correction has been made in the 

 text of my paper, but the diagram given on fig. 7 is in this respect misleading. Lahille 

 also states that the horizontal membranes are very little developed, but this is by no means 

 the case in the Plymouth specimens. 



I have stated above (p. 55) that my discovery of internal longitudinal bars in the Naples 

 Perophora will probably necessitate the creation of a new species j but from Lahille's 

 description this species would appear to be identical with his P. hanyulensis. The Naples 

 species diflers widely from P. viridis as regards its musculature, a fact which thus militates 

 against Professor Herdman's suggestion tliat P. hanyulensis is a synonym of P. viridis. 



W. G. 



