572 PEOF. w. A. herdman's bevised 



Branchial sac with several slight folds on each side ; meshes 

 square, no stigmata. No spicules present in the walls of the 

 vessels. 



Dorsal lamina a plain membrane. 



Tentacles compound. 



Gonads a single gland on each side. 



This genus contains the single species Fungulus cinereus, 

 Herdm., dredged during the ' Challenger ' Expedition in the 

 Southern Ocean from a depth of 1600 fathoms. 



CiTLEOLUS, Serdman, 1880. 



Body fixed, pedunculated, more or less ovate ; the anterior 

 end, where the long peduncle is attached, is narrower than the 

 posterior. Branchial aperture more or less triangular; atrial 

 aperture bilabiate. 



Test cartilaginous, often very thin, usually rough and papil- 

 lated on the outer surface. 



Mantle thin, musculature not greatly developed. 



Brancldal sac with about 6 longitudinal folds on each side ; 

 consisting of transverse vessels and internal longitudinal bars, 

 forming a wide-meshed network. There are no stigmata, the 

 fine longitudinal vessels being absent. The larger vessels, espe- 

 cially the internal longitudinal bars, are supported by a system 

 of branched calcareous spicules. 



Endostyle also strengthened by numerous branched calcareous 

 spicules. 



Dorsal lamina represented by a series of triangular languets. 



Tentacles compound. 



Alimentary canal relatively small, placed posteriorly on the left 

 side ; stomach ventral, intestine turned anteriorly and dorsally, 

 and rectum running posteriorly. 



Gonads on the inner face of the wall of the peribranchial 

 cavity, developed on both sides of the body. 



This is one of the most remarkable and characteristic of the 

 abyssal genera of Ascidians. The seven known species were ail 

 discovered during the voyage of the ' Challenger.' 



The species may be distinguished by external features as 

 follows * : — 



* Por <a table of distinguisLing characters taken from internal structure, see 

 ' Oiiallenger ' Eeport, part i. p. 126. 



