624 PEOF. W. A. HEEDMAN S EETISED 



Branchial sac usually well developed. 



Alimentary canal large. Stomacli-wall folded transversely. 



Postahdomen long. 



The species of Atopogaster are as follows : — 



fAscidiozooids arranged in distinct circular systems. 

 A. gigantea, Herdm. (Mag.) 

 Systems inconspicuous 1 



-, fAscidiozooids large, more than 1 cm. in length 2 



I Ascidiozooids small, less than 1 cm. in length 3 



o /Colour orange A. aurantiaca, Herdm. (Austr.) 



I Colour light grey A. informis, 'S.^vdnx. (i) 



n f Colour yellowish grey A. elongaia, Hevdm. (Mag.) 



{ Colour paler, dull whitish grey A. ebngata, i&v. pallida. (S. Atl.) 



SiGiLLiKA, Savigny, 1816. 



Colony elongated, pedunculated, attached. 



Test gelatinous. 



Ascidiozooids xerj long, divided into thorax, abdomen, and 

 postabdomen. Brancbial and atrial apertures both 6-lobed. 



Branchial sac very short. No internal longitudinal bars. 



Alimentary canal forming an abdomen which is larger than 

 the thorax. Stomach-wall folded longitudinally. 



Gonads in the very long slender abdomen, which is prolonged 

 down through the colony and its peduncle. 



This contains the single species Sigillina australis, Savigny, 

 from the S.E. coast of Australia. 



Stnoicum (Fhipps, 1774), Sav. 1816. 



Colony sessile or pedunculated. Each system forming a sepa- 

 rate club-shaped mass ; systems simple. 



Test semi-cartilaginous, not sandy. 



Ascidiozooids divided into thorax, abdomen, and postabdomen. 

 Branchial aperture 6-lobed, and atrial 6-lobed but irregular, the 

 three anterior lobes being large. 



Branchial sac long. No internal longitudinal bars and no 

 papillae. Many rows of stigmata. 



Alimentary canal forming an abdomen as large as thorax ; 

 intestine not twisted. Stomach-wall areolated. 



Gonads in a postabdomen of moderate length, not separated 

 from abdomen by constriction. 



This contains the species Synoicum turgens, Phipps, from Spitz- 

 "bergen. 



