CLASSIFICATIO]S" OF THE TUNICATA. 593 



{Dorsal tubercle irregular, aperture broken up into 4 distinct sections. 

 A. li/jcrafa, Sluit. (Mai.) 

 Dorsal tubercle normal, aperture not broken up. 

 A. limosa, Sluit. (Mai.) 



QQ r Body pear- sbaped ^. j>^?-//b?'«i/s, Herdm. (Austr.) 



" \ Bodj' not pear-sbaped 30 



Dorsal tubercle semilunar in sbape 31 



Dorsal tubercle not semilunar '6'1 



i Test transparent A. stydoidcs, Traust. (W. Ind.) 



31 \ Test tbick and soft, not transparent. 



[ A. mcridionaUs, Herdm. (S. Atl.) 



(Atrial aperture not more tlian \ way down body. 

 A. CkalkvfferijlELevdm. (A. Arct.) 

 Atrial aperture more tban J way dowu body. 

 A. mmitida *, O. F. M. (N.W. Eur. & Med.) 



nr f Dorsal tubercle longer antero-posteriorly than laterally 33 



I Dorsal tubercle longer laterally tban antero-posteriorly 34 



1 Dorsal tubercle beart-sbaped. 

 A. trunccda, Herdra. (N.W. Eur.) 

 Dorsal tubercle serpentiform. 

 A. translucida t, Herdm. (A. Arct.) 

 Qo f Stigmata 2-6 in a mesh... A.fusiformis\, Herdm. (N.W. Eur.) 



\ Stigmata 6-8 in a mesh 35 



{Test soft, easily torn ; stigmata long and narrow. 

 A. 'placenta, Herdm. (A. Arct.) 

 Test not soft ; stigmata rather short. 

 A. lata, Herdm. (N.W. Eur.) 



cy. [Body partly incrusted with sand, &c 36 



" \ Body not incrusted with sand 37 



( Body of a dull green colour, tentacles about 70. 



36 



A. plebeia, Aid. (N.W. Eur. & Med.) 



j Body not of a green tint, tentacles 10-15 



[_ A. caudata, Heller. (S. Atl.) 



0)7 I Dorsal lamina with a plain edge 38 



Edge of dorsal lamina not plain 39 



(Test thick, cartilaginous, opaque, but with no adhering prolongations. 

 A. q^LUidrata, Traust. (Med.) 

 Test rather thin and transparent, with prolongations round the area 

 of attachment 40 



(Siphons long, conspicuous ; tentacles 60. 

 A. canaliculata, Heller. (S. Atl. & Mai.) 

 Siphons short, wart-like, inconspicuous ; tentacles 40-50. 

 A.frostrata, Heller. (W. Ind.) 

 on / Test very dark coloured... A.fumigata, Grube. (Med., N.W. Eur.) 



Not of a dark colour 41 



r No dorsal tubercle, neural gland opening into atrium. 

 41 J A. Marioni, Eoule. (Med.) 



[ Dorsal tubercle present, with neural gland opening on it 42 



* The number of tentacles in this species seems variable. Ascidia incrasiatd, 

 Heller, also comes in here, but cannot readily be distinguished from the de- 

 scription. 



t Sluiter has just described a new species from the Malay Archipelago under 

 this name " tratislucida." It is, however, quite distinct from the ' Challenger ' 

 species, and will require to be renamed. 



\ The A. Olrilcii of Traustedt (1883), described by him in 1880 under the 

 name of A. mentula, seems indistinguishable from this species. 



