REPORT ON THE TUNICATA. 139 



Cynthia formosa, Hcrdman (PI. XVI. figs. 1-5). 



Cynthia formosa, Herdman, Prelim. Rep., Proc. Roy. Soc. Edin., 1880-81, p. 58. 



External Appearance. — This species has a spherical body and a narrow stalk. 

 The posterior end of the body is rounded, and the anterior is rather flatter; the 

 dorsal edge is slightly more convex than the ventral. The stalk is about as long as 

 the body, it is twisted and narrow, but expands slightly at the lower end where it is 

 attached. The apertures are both at the anterior end ; they are not distant, and are 

 prominent. 



The surface is smooth on the posterior half of the body, and is covered with fine silky 

 spines on the anterior half ; these increase in size towards the anterior end, and culminate 

 in sheaves of long bristles, which surround and hide the apertures. The colour is grey. 



Length of the body, T5 cm., breadth of the body, 13 cm. ; length of the stalk, 1/6 cm. 



The Test is thin but tough ; it is semi-transparent on the posterior half of the body 

 only. 



The Mantle is thin but muscular ; the muscle bands form a close net-work. 



The Branchial Sac has six folds upon each side. The internal longitudinal bars 

 are ribbon-like, and there are about eight on a fold and four in the interspaces. The 

 transverse vessels are rather wide and are all of one size. The meshes are transversely 

 elongated, and are divided usually by three narrow membranes ; they contain each nine 

 or ten stigmata. 



Tlie Dorsal Lamina consists of a series of small closely-placed languets, borne on the 

 edge of a broad lamina. 



The Tentacles are large and much branched, and are about twelve in number. 

 Between these are a series of much smaller but also compound tentacles, placed usually 

 two between each pair of large ones, and these again are separated by very minute simple 

 proj ections. 



TJie Dorsal Tubercle is simple ; it is transversely elliptical, with the opening anterior, 

 and the horns turned inwards. 



This is a most elegant little species, and seemed at first sight, with its delicate peduncle 

 and the coating of bristles upon the anterior end of the body, as if it might require to be 

 separated generically from its congeners. It is, however, in internal structure quite a 

 typical Cynthia, but it is the only one which has what may properly be called a peduncle 

 (PI. XVI. fig. 1). Here that organ really merits its name ; it is thin and stalk-like, and 

 fully as long as the body. The coating of hairs is very peculiar. It is only present upon 

 the anterior end of the body, and around the terminally placed apertures it is exaggerated 

 to form two clumps of bristles which terminate the body, anteriorly. The test upon the 

 posterior half of the body is thin and semi-transparent and has no hairs. 



(ZOOL. CHALL. EXP. — PAKT XVII. — 1882.) R 19 



