NoTT. — On N.Z. Composite Ascidians. 315 



"pharyngeal tubercles " are very frequently, though seemingly 

 not always, met with. Between the zooids there extends 

 usually a wide and deep cavity, arched above, but flat below, 

 where a second layer of test parallel to the surface runs, as 

 said above, along the colony at about the level of the oeso- 

 phagus (fig. 1). The drawing (fig. 1) gives the arrangement 

 actually seen in very many cases, which is, however, by no 

 means universal (see fig. 2 for comparison). Beneath the 

 second layer the test is compact, and has cavities only for the 

 zooids and developing embryos. 



Vascular appendages are uniformly present, springing from 

 the region above the oesophageal constriction (fig. 2, v.ap.). 

 They do not usually end in terminal vessels. 



The zooids are remarkable for their greatly elongated 

 thoracic region (figs. 2 and 7), and long extension of the 

 oesophagus above its constriction. 



The branchial siphon (fig. 5, and fig. 7, h.s.) is compara- 

 tively short, and quite narrow in spite of the large size of the 

 stellate opening. As seen in longitudinal section it presents 

 the form shown in fig. 5, the test-matrix containing spicules, 

 &c., being projected downwards in the form of triangular lobes 

 around the upper edges. The buccal tentacles are few in 

 number, and of two sizes, all much shorter than in L. niveum 

 or L. dcnsum. Their ends are rounded, and not pointed. 



The branchial basket is of extreme delicacy, the mantle 

 being quite transparent usually. Owing to the vacuolated 

 character of the test in the pharyngeal layer the zooids are 

 usually much displaced and. contorted, rendering observation 

 as to details difficult. I have, however, succeeded in obtain- 

 ing a good detail figure (fig. 6) for comparison. The stigmata 

 are long and narrow, the fringing cells being convex and dis- 

 tinctly outlined on the stigmatic, but straight and faintly 

 marked off on the vascular, surfaces. The large oval nuclei lie 

 near the vascular border. Cilia are only faintly distinguish- 

 able. The transverse vessels are plain, and scarcely wider 

 than the longitudinal. Only three rows of stigmata are 

 observable in the adult, but four are always present in the 

 young form (fig. 7). 



The endostyle offers no peculiarities ; it is always distinct 

 and very undulating in outline (fig. 1, en.). The dorsal 

 lamina is represented by a series of very long languets, broad 

 at the base, but pointed distally (fig. G, d.l.). More remark- 

 able is the fact that the stigmata on either side are scarcely 

 more widely disparted than in the remainder of the pharyngeal 

 basket. 



The pei'ipharyngeal band is usually very distinct as a 

 broad circlet of deeply -stained cells below the buccal tentacles 

 (fig. 6,2yp.h.). 



