204. THE VOYAGE OF H.M.S 



The apertures are conspicuous and distinctly lobed (PL XXX. figs. 1 and 2). The 

 atrial aperture is not distant from the branchial and is always more prominent. 



The testis that of a typical Ascidia, and contains numbers -of large oval or spherical 

 bladder-cells, especially in the outer layers (PL XXX. fig. 3, bl.). Vessels are abun- 

 dant and branch freely, but their terminal knobs (PL XXX. fig. 3, t.k.) are rather small. 



The branchial sac is very like that of Ascidia mentula. It has the same irregularity 

 in the disposition of the stigmata, as seen from the inside, caused by a sbght longitudinal 

 plication. The internal longitudinal bars are strong, and with their prominent curved 

 papillae form a conspicuous feature in the internal view of the sac (PL XXX. fig. 4). 

 Delicate horizontal membranes are present along the inner edges of the transverse vessels, 

 extending between the papillae, and also frequently in intermediate positions connecting the 

 small papilla?. 



The dorsal lamina, as may be seen from a glance at figures 5, 6 and 7 on Plate XXX., 

 varies considerably in its characters. Figure 6 shows what seems an unusual condition, 

 where the edge is crenated, and bears a number of small irregularly placed pointed pro- 

 cesses. The most prominent of these are always placed opposite the terminations of the 

 ribs. Figure 7 represents the right side of the lamina, near the base. 



The dorsal tubercle (PL XXX. fig. 8, d.t.) is very large, and in the specimen 

 figured was not nearly contained within the shallow peritubercular area. In another 

 individual which was examined, the peritubercular area was much deeper and more cup- 

 shaped. It enclosed almost the whole of the tubercle. The anterior peripharyngeal band, 

 which is in close relation to the posterior end of the dorsal tubercle, lies at a considerable 

 distance from the dorsal ends of the right and left posterior bands, which turn posteriorly 

 and converge towards the anterior extremity of the dorsal lamina (PL XXX. fig. 8, p.p.). 

 The tentacles are comparatively short but stout. 



1 This specimen was attached by the left side of the body, and has no posterior prolongation. 



2 The posterior prolongation was torn in this specimen. 



