CLASSIFICATION OF THE TUNICATA. 565 



Body pyriform, stalk short, stigmata mostly curved. 



A. gigantea, Herdm. (Kerguelen Isl.) 

 Body club-shaped, stalk long, stigmata mostly straight. 



A. pedunciUafa, Herdm. (Kerguelen Isl.) 



Peea, Stimpson, 1852. 



Body attached or free, may be slightly stalked. 

 Test sandy or not. 



Branchial sac with five folds on each side. Stigmata in spirals 

 or in rows. 



This genus (which is simply those Molgulids with five folds 

 only on each side of the branchial sac) contains four species*: — 



("Test delicate and transparent P. chrystalUna, Moll. (N. Atl.) 



I Test opaque and more or less sandy 1 



(With very long branchial and atrial siphons. 

 P. longicolUs, Wagner. (Arct.) 

 With the siphons short or inconspicuous 2 



p /Stigmata of branchial sac curved... P. Hancocki,'KeTd.m. (N.W.Eur.) 

 "^ 1 Stigmata straight P. Carpenteri, Herdm. (N. Atl.) 



Ctentcella t, Lacaze-DutJiiers, 1877. 



Body fixed. 



Test covered with sand. Branchial and atrial lobes laciniated 

 or cleft at their edges into numerous sharp processes. Atrial 

 siphon furnished with a bilobed valve. 



Branchial sac with seven folds on each side. Stigmata spirally 

 coiled, arranged in infundibula. 



Dorsal lamina with the margin toothed. 



Gonuds present on both sides of the body. 



The four species of Ctenicella may be distinguished thus : — 



Dorsal tubercle horseshoe-shaped C. Lanceplaini, Lac.-Duth. 



(N.W. Eur.) 

 Dorsal tubercle S-shaped 1 



* Fera Huxleyi, Macd., is a Ehodosoma (see Ascidiidse). 



t Molgula complanata, Aid. & Hanc. (N.W. Eur.) may belong to this genus. 

 If so, it differs from the other species of Ctenicella in haying only 6 folds on 

 the left side (right, of Hancock) of the branchial sac. Lithone]^hrya eugyranda 

 of Giard probably belongs to Ctenicella. 



