REPORT ON THE TUNIOATA OP PLYMOUTH. 81 



Fig. 5. — Perophora Listeri, Wieginann. Dorsal wall of pharynx, showing 

 dorsal lamina and aperture of hypoganglionic gland, seen from inside. Zeiss, 

 A, Oc. 2, Cam. luc. 



p.g. = Pericoronal groove. 



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



g. = Ganglionic mass. 

 d. I. = Longitudinal membrane of dorsa lamina. 

 I. = Marginal languettes. 

 h.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. 



I. = Marginal languettes, interserial in position. 

 i.p,= Small marginal projections intermediate between the languettes. 



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

 inside. Magnified, slightly diagrammatic. 

 h.m. — Horizontal membranes. 

 i. I. b. = Internal longitudinal bars. 



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



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

 Cam. luc 



h.m. = Horizontal membranes. 



Postsceipt. 



By Professor Herdman's kindness I have recently been enabled to con- 

 sult Lahille's important Hecherches sur les Tuniciers. Lahille points out 

 that the appearance of papillae on the internal longitudinal bars of the 

 branchial sac of Diazona violacea, as previously described by Savigny and 

 Delia Yalle, is a false one, produced by the thickened remains of the 

 "primitive branchial languettes." I had myself, like Alder, failed to find 

 any such vertical papilla as were represented by Savigny for this species, and 

 was struck by their apparently recumbent position in mounted preparations 

 (see fig. 7) ; but a re-examination by means of dissecting needles has con- 

 vinced 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 bttle developed, but this is by no means 

 the case in the Plymouth specimens. 



I have stated above (p. 71) that my discovery of internal longitudinal bars 

 in the Naples Perophora will probably necessitate the creation of a new 

 species; but from Lahille's description this species would appear to be 

 identical with his P. banyulensis. The Naples species differs widely from 

 P. viridis as regards its musculature, a fact which thus militates against 

 Professor Herdman's suggestion that P. banyulensis is a synonym of P. viridis. 



W. G. 



