80 WALTER GARSTANG, M.A. 



sufficient ground for generically separating these two forms, I believe 

 Forbes and Goodsir's species to be perfectly distinct, and to possess 

 the following distinguishing characters : 



Orifices not divided into lobes, evenly rounded, 



Zooids projecting freely by their thoracic portions, which are 

 united to the common mass by a slightly contracted but not pedun- 

 culated oesophageal region. 



Branchial sac with thirteen transverse rows of oblong stigmata ; 

 a hooked interserial papilla (connecting duct) at the intersection of 

 every longitudinal (interstigmatic) and transverse bar. 



Oviduct absent (?) 



But the whole matter is so beset with doubts that it is greatly 

 to be desired that specimens should be obtained again from the 

 Hebrides, and their anatomy re-described. Unfortunately Giard gives 

 no anatomical details of the Diazona dredged by him and described 

 in Comptes Rendus, ciii, p. 755, 



DESCRIPTION OF PLATE II. 



Illustrating Mr. W. Garstang's " Report on the Plymouth Tunicata," 



pt. 1. 



N.B. — Where not otherwise stated all the figures were drawn from preserved 



material. 



Fig. 1. — Clavelina lepadiformis, O. F. Muller. Three of the dorsal languettes 

 of the branchial sac. Zeiss, A, Oc. 2, Cam. 

 d.s. = Dorsal sinus. 

 h.m = Horizontal membrane. 

 Fig. 2. — Pycnoclavella aurilucens, gen. et sp. nov. Portion of a colony. A 

 section has been taken through the colony in order to show the common test 

 and the imbedded portion of the zooids. Nat. size ; slightly diagrammatic. 

 c.t. = Common test. 

 t.p. = The free portions (thoracic and oesophageal) of the zooids pro- 



jecting from the common test. 

 v. p. =The visceral portions of the zooids imbedded in the common test. 



Fig. 3. — Pycnoclavella aurilucens, 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, Wiegmann, Portion of the branchial sac. Zeiss, 

 A, Oc. 2, Cam. luc. 



h.m. = Rudimentary horizontal membranes. 



p. = Interserial papillae (=rudimentary connecting ducts). 



