CLASSIFICATIOir OP TIJE TUIflCATA. 621 



PoLTCLiNoiDES, voTi Drasche, 1883. 



Colony forming rounded transparent masses. 



Systems irregular. 



Test transparent. 



Ascidiozooids divided into thorax, abdomen, and postabdomen. 

 Branchial aperture 6-lobed. Atrial aperture placed far back on 

 the dorsal edge and not lobed ; anterior to it is an atrial lauguet. 



BrancTiial sac with 8 rows of stigmata. No internal longi- 

 tudinal bars and no papillae. 



Alimentary canal not twisted. Stomach with numerous flat 

 longitudinal folds. Anus provided with two large lobes. 



Gonads in a moderately long postabdomen, separated from the 

 abdomen by a slight constriction. 



This contains the species FolycUnoides diaphanum, v. Drasche, 

 from Mauritius. 



Aplidium, Savigny, 1816. 



Colony massive or lobed, not pedunculated. 



Systems compound and irregular. 



Ascidiozooids not much elongated. Branchial aperture 6-lobed ; 

 atrial lobed, or having a more or less rudimentary languet, and 

 placed far back. 



Test gelatinous or cartilaginous, rarely sandy. 



Brancliial sac fairly well developed. 



Alimentary canal of moderate size. Stomach-wall folded lon- 

 gitudinally. 



Postaldomen usually short. 



Those species of the genus which have been sufficiently cha- 

 racterized can be distinguished thus : — 



/Atrial aperture distinctly lobed or -with a languet 1 



\ Atrial aperture with no visible lobes or languet 2 



, f Atrial aperture 6-lobed 3 



\ With an atrial languet 4 



(Colony sandy ; branchial sac not pigmented. 

 A. asperum, v. Dr. (Med.) 

 Colony not sandy ; branchial sac pigmented. 

 A. 'pellucidum, v. Dr. (Med.) 



. f Atrial languet bifurcated A. fuscum, Herdm. (A. Arct.) 



I Atrial languet not bifurcated 5 



- riO grooves on stomach A. fallax,Z ohns. (N.W. Eur.) 



I 4 grooves on stomach .■ 6 



(Brown pigment-dots on dorsal edge of thorax. 

 A. tremulum, Sav. (Red S.) 

 No such pigment-dots 7 



