REPORT ON THE TUNICATA. 109 



homogeneous, and contains only small rounded protoplasts. In several sections examine I 

 no vessels were found ; so that, if they are present in this test, they must be few in number. 



Sections through the peduncle (PI. XII. tig. 2) show it to have a structure very similar 

 to that of Cideolus murrayi. The matrix is like that of the test covering the body, and 

 contains similar minute rounded protoplasts. It is perforated by several large holes 

 (PI. XII. peel, c), the sections of large tubes running longitudinally along the peduncle, 

 and each of them containing a large blood-vessel in its interior. 



The outer surface of the peduncle has adhering to it a considerable quantity of sand- 

 grains, Foraminifera, shell fragments, &c, and in the sections one finds similar particles 

 imbedded iu the matrix often far distant from the surface (PI. XII. figs. 1 and 2). 

 These have doubtless become surrounded by the outward growth of the peduncle. 



Tin- Mantle is very thin, and has the form of a delicate membrane adhering closely to 

 the inner surface of the test, from which it is separated with difficulty. The musculature 

 is feeble, consisting of a scries of distant transverse bands crossed by slighter and more 

 irregular longitudinal bands. 



The Branchial Sac is a coarse network — the vessels being strong for the size of the 

 body. There are several longitudinal folds on each side of the sac, but they are very 

 slight. The internal longitudinal bars are wide and prominent. They are regularly 

 placed, and are apparently the strongest part of the network. The transverse vessels 

 are all of the same size, but they are irregular, and are much slighter than the internal 

 longitudinal bars. Usually the meshes are rather large and are elongated longitudinal I v 

 (PI. XI. fig. 5, and PI. XII. fig. 3) — the breadth being about three-fourths of the 

 length, but occasionally irregularly placed intermediate transverse vessels (PL XL fig. 5,tr'.) 

 are present, and sometimes oblique or longitudinal vessels (I. v.), usually of small calibre, 

 are given off from the transverse vessels, thus breaking the mesh up into compartments, 

 and suggesting the formation of true stigmata. 



The calcareous spicules are not at all prominent, on account of their small size, but 

 they are pretty numerous, and often ramify considerably (PL XL fig. o, and PL XII. fig. 

 .".. sp.). They are mostly more branched and more irregular than those of cither Cuholus 

 murrayi or Calculus wyville-thomsoni. As usual they are present chiefly in the internal 

 longitudinal bars. 



The Endostyle is broad and distinct. The prominent edges have a creamy white tint, 

 while the groove is brown (PL XII. tig. 4). 



Calcareous spicules are not present in such numbers as in either of the preceding 

 species. The raised edges (w. e.) in which they are situated are semi-transparent, ami each 

 equals in breadth about one-fifth of the breadth of the entire organ. The spicules are 

 large and considerably branched but are not numerous. They resemble those of the 

 central part of the endostyle of Culeohis murrayi. 



Laside each edge is an opaque brown area of about the same breadth as the edge (l.b.b.), 



