1G2 THE VOYAGE OF H.M.S. CHALLENGER. 



The dorsal lamina is in a condition rarely seen in the genus Styela. It is narrow, 

 and the free margin is cut into a series of wide triangular notches, leaving outstanding 

 teeth between them (PI. XX. fig. 5). The membrane is also ribbed transversely; a long rib 

 runs up the centre of each tooth to the apex, while between each pair of these there are 

 a number (about six) of shorter ribs which do not reach the margin. This lamina presents 

 a condition of affairs intermediate between the usual plain smooth-edged membrane of 

 the typical Styela, and the large distinct languets of Styela bythia. 



The tentacles are of three sizes, placed so that if we call the largest A, and the 

 smallest C, they have the following arrangement : — A, C, B, C, A, &c. (PI. XX. fig. 

 6, tn., tn.' and hi."). The peritubercular area is very large, and is much deeper than the 

 dorsal tubercle, which is small and occupies merely the apex. Both horns are turned to 

 the right, the one outwards and the other inwards (PI. XX. fig. 6, d.t.). 



The intestine is a narrow tube, and the loop which it forms is rather wide, — another 

 point in which this species differs from the typical members of the genus. 



One specimen of Styela fiava was dredged in the South Atlantic, off the coast of 

 Buenos Ayres, at Station 320; February 14, 1876; lat. 37° 17' S., long. 53° 52' W.; 

 depth, 600 fathoms ; bottom temperature, 2° - 7 C; bottom, hard ground. 



Styela glans, Herdman (PL XX. figs. 10-13). 



Styela glans, Herdman, Prelim. Eep., Proc. Eoy. Soc. Edin., 1880-81, p. 65. 



External Appearance. — The shape is regular, and is between conical and hemi- 

 spherical. The highest point of the body is at the ventral edge of the anterior end. The 

 posterior end is large and flat, and is attached to a piece of coral. The dorsal edge is 

 more convex than the ventral. The branchial aperture is anterior, and is placed at the 

 highest part, near the ventral edge ; the atrial is on the dorsal edge, two-thirds of the 

 way down ; both are sessile and inconspicuous. 



The surface is roughish, but regular. The colour is a dark reddish-brown. 



Length of the body, l - 5 cm. ; breadth of the body, 1"2 cm. 



The Test is not thick, but is tough ; it is white on the inner surface. 



The Mantle is very thin and membranous. 



The Branchial Sac has four slight folds upon each side, about five internal longi- 

 tudinal bars being crowded together, and the same number placed further apart alternately. 

 The meshes are elongated antero-posteriorly, and contain three stigmata each. They are 

 divided transversely by narrow membranes. 



Tlie Dorsal Lamina is a narrow membrane. 



The Tentacles are simple ; they are few and of moderate size. 



Tlie Dorsal Tubercle is simple ; it is nearly circular in outline. 



This is a small regularly shaped species, rather like an acorn in appearance (PL XX). 



