604 PBOE. W. A. HEBDMAN S KEVISED 



quite willing that both should be placed merely as subgenera of 

 Clavelina ; but I consider that it is convenient to separate off under 

 a distinct name groups of species which resemble one another, 

 but differ from the rest, in some marked characteristic. . 

 The species of Stereoclavella are as follows : — 



J Dorsal languets short 8. ohlonga, Herdm. (Atl.) 



I Dorsal languets very large 1 



( Horizontal membranes of the branchial sac wide. 

 X J 8. enormis, Herdra. (S. Atl.) 



[ Horizontal membranes narrow 8. australis*, Herdm. (Austr.) 



Clayelina, Savigny, 1816. 



Body elongated, club-shaped, but with no peduncle beyond 

 the abdomen ; attached to a delicate, branched, creeping stolon 

 from which buds are formed ; divided into thorax and abdomen. 



Test thin, gelatinous, or cartilaginous. Apertures circular, not 

 lobed. 



Mantle thin, muscles mainly longitudinal. 



Branchial sac without internal longitudinal bars. Stigmata 

 straight, no papiliiform connecting-ducts. Horizontal membranes 

 present. 



Dorsal lamina represented by languets. 



Alimentary canal extending behind the branchial sac to form 

 a well-marked abdomen. 



This genus, in the restricted sense in which it is used here, 



contains only half a dozen species t, some of which, however, are 



imperfectly characterized. 



/Thorax and abdomen of much the same size 1 



[Abdomen much longer than thorax 2 



(Only 2 rows of stigmata in branchial sac. 

 C. pm7iilio\, M.-Edw. (N.W. Eur.) 

 At least 6 rows of stigmata 3 



o f 6 to 8 rows of stigmata C. na7ia^, Lah. (N.W. Eur., Med.) 



\ 12 to 16 rows of stigmata 4 



r With yellow or brown lines of pigment on the thorax. [Med.) 



^ J C. lepadiforviis §, O. E. M. (N.W. Eur., 



] With white lines of pigment on thorax. 



\ C. Eissoana, M.-Edw. (N.W. Eur.) 



r Only 3 or 4 rows of stigmata. C. producta, M.-Edw. (N.W. Eur.) 

 2 \ About a dozen rows of stigmata. 

 [ C. Savigniana, M.-Edw. (N.W.Eur.) 



* This species will be described in the Catalogue of Tunicata of the Australian 

 Museum. 



t Possibly O. F. Miiller's Ascidia gelatina is a Clavelina, 



X Possibly the young of C. lepadiformis or some other species. 



§ With several varieties. 



