NoTT. — 0)1 N.Z. Comi^osite Ascidians. 317 



The spicules are extremely small, and vary much in size 

 (fig. 3). On a surface-view they appear most numerous 

 around the branchial pore (fig. 4), being absent in the inter- 

 vals. In longitudinal sections a layer occurs at the level of 

 the buccal tentacles, which is fairly well supplied with 

 spicules, most numerous round the zooid. In the lower layers 

 they are few or quite absent (fig. 2), being met with princi- 

 pally near the oesophageal constriction. 



Histologically, the test exhibits a structureless matrix, 

 with very numerous nucleated test-cells throughout. The 

 surface layer is characterized by its large oval bladder-cells 

 (fig. 5), which, with borax-carmine, appear finely granular, 

 nuclei being often visible in the walls (fig. 5, nc). These 

 cells are also met with rarely in the lower parts of the test. 



Vacuoles (fig. 2, i?.) of large size occur below and among the 

 abdominal prolongations of the zooids. In some few instances 

 these unite with the cloacal canals (ex.). The thoracic region 

 of the test also shows irregularly-quadrilateral chambers and 

 passages, recalling those of L. tuberatum, as shown in fig. 2. 

 This arrangement is, however, quite unusual, the rule being 

 for the test to be perforated with wide cloacal canals, which 

 here and there enlarge greatly. 



Ectodermal prolongations of the mantle are of frequent 

 occurrence, usually ending in a bulb (fig. 1, v.ap.). 



The zooids are much elongated, occupying a relatively 

 deeper layer of the test than in the former species considered. 

 Most remarkable is the great length of the cesophago-rectal 

 region, which with its mantle envelope often exceeds by one- 

 half the length of the thorax. This region is also, in many 

 cases (fig. 2), continued below the constriction (which is always 

 very definite) for some distance before the abdominal dila.tation 

 commences. 



The branchial siphon is of considerable length (figs. 1 and 

 2, b.s.), and of remarkable form. The edge (branchial pore) is 

 quite plain. For some distance the siphon is fairly even in 

 size ; it then dilates greatly, forming a bottle-shaped mass 

 (fig. 8, b.d.), constricting once more slightly at the muscular 

 band from which the tentacles arise. It thus resembles a 

 water-bottle. In fig. 8 the mantle ectoderm is shown at a 

 shght distance. The buccal tentacles (fig. 7, b.t., and fig. 8) 

 are long and numerous. In every case the branchial pore is 

 found occupying a depression in the surface (figs. 1 and 2). 



Four rows of branchial stigmata are present : in every case 

 they are indistinguishable in the adult except in cross-sections. 

 The young zooids show four rows, with apparently five in each 

 row (fig. 6, b.st.). 



As seen in section the endostyle is peculiar. It shows an 

 internal cavity of large size, from which arise several smaller 



