1:n the voyage of h.m.s. challenger. 



apertures are prominent ; they are placed at the extremities of the two projections formed 

 by the cleft ; the branchial projection is terminal, the atrial is on the dorsal edge, fully 

 half way from the anterior to the posterior end, and is not so long as the branchial. 



The surface is very irregular, and is much wrinkled and rough ; on the right side the 

 chief wrinkles run transversely. The colour is yellowish-brown. 



Length of the body, 2 cm. ; breadth of the body, 1 - 6 cm. 



The Test is strong and stiff; it is white on the inner surface. 



The Mantle is thick and moderately muscular. 



The Branchial Sac has six folds on each side. There are six internal longitudinal 

 bars on each side of a fold, and three in the interspace. The transverse vessels are wide, 

 and are of two sizes placed alternately. The meshes, which are transversely elongated, 

 contain each six to eight oval stigmata, and are sometimes divided by a narrow hori- 

 zontal membrane. 



T7te Dorsal Lamina has the free edge terminated by a series of tentacular languets. 



The Tentacles are simply pinnate, and are about twelve in number. 



The Dorsal Tubercle is large and irregularly oblong, and the aperture is anterior ; 

 both horns are turned to the left. It lies in a small, but deeply cup-shaped perituber- 

 cular area. 



This curious little species looks, on account of the prominent anteriorly placed 

 branchial and atrial apertures, as if the anterior end of the body had been deeply cleft 

 (PI. XV. fig. 8). In this respect, and in the markings on the surface, the species is rather 

 like Cynthia dura, Heller, 1 from which it differs in the number of tentacles, the shape of 

 the dorsal tubercle and several other particulars. 



Cynthia Jissa is also like Cynthia irregularis in some respects. The external 

 appearances are not very dissimilar, and the branchial sacs are very much alike in their 

 minute details (compare PL XV. fig. 9, and PI. XVI. fig. 11), but they differ in their 

 coarser anatomy, as Cynthia irregularis has fourteen folds while Cynthia Jissa has only 

 twelve. The dorsal tubercles of the two species are entirely different. 



The tentacles in Cynthia Jissa are scarcely compound (PL XV. fig. 11). They 

 look like the tentacles of a Styela, with a series of small buds projecting from each side. 

 The dorsal tubercle is of the simple form very commonly found in Ascidia, and is 

 deeply cup-shaped, with both horns turned to the left. 



Several specimens were found adhering to the test of Microcosmus polymorphous, from 

 Station 162, April 2, 1874 ; off East Moncceur Island, Bass Strait; 38 to 40 fathoms ; 

 bottom sandy. 



1 Untersuclmngi/n ii. d. Tunic, des adriatischen Meeres, Abtli. 3, p. 11, pi. iii. fig. 1. 



