SOME ASCIDIANS PROM THE ISLE OF WIGHT. 153 



Fig. 5. — A. mollis. The large abnormal individual, nat. size. 



a. = View from above the dorsal surface. The left side consists entirely 

 of the area of attachment ; the right side forms an elevated 

 ridge. The inconspicuous slit-like oral and cloacal apertures 

 are indicated. 



6. = View of the opposite surface. 



Fig. 6. — A. mollis. The same with the test removed, in the same position 

 as in fig. 5 a. Nat. size. 



cm. = Anus. 

 c.s. = Cloacal siphon. 

 gn. = Ganglion. 



int. = Intestine — the descending portion. 

 ces. — (Esophagus. 

 o.s. = Oral siphon. 

 ov. = Oviduct, 

 pc. = Pericardium. 



st. = Stomach, covered with renal vesicles. 

 a.(L = Vas deferens. 



PLATE VI. 



Fig. 7. — Ascidia depressa, Alder. The largest individual, twice the natural 

 size. 



Fig. 8 — A. depressa. The same, with the test removed, viewed from the 

 left side, showing the course of the viscera, and the rather elongated siphons. 



Fig. 9. — A. depressa. A portion of the test, magnified, showing the 

 papillae on its surface. 



Fig. 10. — A. depressa. A portion of the dorsal lamina, magnified, showing 

 the marginal teeth (m.t.) and the lateral papillae which project from its 

 concave surface. Camera lucida. 



Fig. 11 a. — A. depressa. A portion of the pharyngeal wall, magnified. 

 Camera lucida, 



h.v. = Horizontal vessels. 

 i 1. 6. = Internal longitudinal bars or vessels. 

 p. — Papillae above the connecting ducts. 

 r.i.p. = Extremely rudimentary intermediate papillae, here and there present 

 where the meshes are elongated. 



Fig. 11 b. — A depressa. An enlarged view of the junction between an 

 internal longitudinal bar li.l.b.) and a horizontal vessel (h.v.) showing the 

 form of the disc-shaped papilla (p.), with its anterior (a. b.) and posterior 

 buttresses. 



