OLASSIFICATION" OF THE TUNICATA. 591 



^Attached by small area at posterior end, lobes of buccal siphon den- 



I ticulated, stigmata 5 in a mesh. 



5-{ A.aspersa*, O.F.M. (N.W. -Eur. &Med.) 



Attached by large area on left side, buccal lobes rounded, stigmata 



1^ 12 in a mesh A. scabra, O. F. M. (N.W. Eur. & Med.) 



AsciDiA, Linn., 1767. 



Body attached, sessile, rarely pedunculated ; free or incrusted 

 with sand. Branchial and atrial apertures not close together ; 

 branchial 8-lobed, atrial 6-lobed f. 



Test cartilaginous or membrauous, soft or hard, usually crowded 

 with large bladder-cells. 



Branchial sac not folded on itself posteriorly ; sometimes 

 minutely plicated. The internal longitudinal bars usually bear 

 papillae. The stigmata are straight ; three smaller transverse 

 vessels between each pair of larger. 



Nerve-ganglion and subneural gland distant from the dorsal 

 tubercle. 



Dorsal lamina a simple membrane wliich maj' be transversely 

 ribbed and have marginal teeth, or may be perfectly jjlaiu. It is 

 continued behind the oesophageal aperture. 



Tentacles simple. 



Alimentary canal on the left side of the branchial sac. 



Gonads iu the intestinal looj). 



Menal concretions always contained in the intestinal wall, 

 never extending into mantle. 



/Test completely invested with sand 1 



\ Test not completely invested with sand 2 



, r Siphons short A. conchileffa, O.F.M. (N.W.Eur.) 



\ Siphons very long A. involuta, Heller. (Med.) 



(Two individuals always found together in a common test. 

 A. diplozoon, Sluit. (Mai.) 

 Individuals occurring separately 3 



o f Branchial sac not plicated 4 



I Branchial sac minutely plicated 5 



. f Stigmata exceeding 7 in a mesh". A. Patoni, Herdm, (N.W. Eur.) 



1^ Stigmata less than 7 in a mesh 6 



„ /Tentacles numerous, about 60 7 



[Tentacles not numerous, about 40 8 



- /Dorsal lamina with plain edge, very slight ribs 9 



\ Dorsal lamina with toothed edge and distinct transverse ribs 10 



(Stomach ovate or globular 11 

 Stomach elongated and sausage-shaped. 

 A. dij7nphniana, Traust. (Arct.) 



* Including Ascidia pustulosa, Aid. & Hanc. 



t Sluiter has just described a species, Ascidia decemplex, from the Malay 

 Archipelago, with ten lobes round each aperture. 



