534 DE9. H. C. SOEBT AND W. A. HEEDMAN ON THE 



priate. No other Ascidians were found at Hooles Bay ; but all 

 parts of it were not sufficiently examined. 



The specific description is as follows : — 



External appearance. — Shape nearly globular (PI. XI. fig. 1), 

 somewhat compressed laterally, and rather elongated antero-pos- 

 teriorly, not attached. Anterior end truncated, slightly produced; 

 posterior wide and rounded; dorsal and ventral edges equally 

 convex. Apertures conspicuous, on large mamilliform projections 

 placed at the dorsal and ventral extremities of the anterior end ; 

 both are directed anteriorly and are obscurely lobed. Surface even 

 and nearly smooth, being merely slightly roughened in places, and 

 having here and there a few particles of sand and fragments of 

 algae attached. This ia especially the case towards the posterior 

 end. There are no hairs or other processes developed, and there 

 is no incrusting coat. Colour milk-white, with here and there a 

 hyaline bluish tinge- Length (antero-posterior) f inch, breadth 

 (dorso-ventral) |- inch, thickness (lateral) g inch. 



Test thick and cartilaginous, but soft and rather flexible, mode- 

 rately tough ; whitish grey in section ; smooth and glistening on 

 the inner surface, with a hyaline blue tinge. 



Mantle very thin and membranous, not adhering to the test ; 

 musculature feeble, chiefly round the posterior end, dorsal and 

 ventral edges, and on the siphons and their immediate neigh- 

 bourhood (PL XL fig. 2). Siphons long and conical ; sphincters 

 not very strong. 



Brancliial sac large, with seven folds on each side ; they con- 

 verge towards the oesophageal aperture ; and the seventh pair, next 

 the endostyle, are very slight. Internal longitudinal bars broad 

 and ribbon-like ; four on the uppermost surface of each fold, and 

 none in the interspaces (PL XL fig. 4). Transverse vessels not well 

 marked, distant, provided each with a wide horizontal membrane. 

 The meshes, formed by the intersection of these membranes with 

 the internal longitudinal bars, are large and elongated vertically. 

 Stigmata rather irregular, in some places much curved, in others 

 almost straight, on account of the secondary vessels being here 

 and there coiled spirally, while between the spirals, sometimes 

 for considerable distances, they are more or less straight and run 

 longitudinally. 



Endostyle rather inconspicuous. The hypopharyngeal groove 

 ends csecally at its anterior extremity, and does not communicate 

 with the right and left peripharyngeal grooves (PL XL fig. 5). 



Dorsal lamina short and not wide (PL XL fig. 6, d. I.) ; a plain 

 delicate membrane with no teeth or ridg-es. 



