J 



CLASSIFICATION OF THE TUNICATA. 613 



Dorsal lamina represented by a series of short langucts. 



Alimentary canal posterior to the branchial sac. Stomach 

 ovate, smooth-walled. 



Gonads placed on the right side of the intestinal loop. The 

 embryos develop in an incubatory pouch formed as a diverticulum 

 from the atrial cavity. The larvae are of large size and are gem 

 miparous. 



The four known species oi DistapUa may be separated thus : — 



{Colony forming a thick incrusting mass. 

 B. lubrica, v. Dr. (Med.) 

 Colony formed of a number of distinct knobs or club-shaped masses... 1 

 f Ascidiozooids and larvse very large ; stomach-wall reticulated. 

 \\ D. magnilarva, D. Valle. (Med.) 



[ Ascidiozooids and larvae of moderate size ; stomach-wall smooth 2 



Knobs of colony with short peduncles or none ; colour rose-red. 



B. rosea, D. Valle. (Med. & N.W. Eur.) 

 Knobs with well-marked peduncLes ; colour dark violet or purple. 



B. Vallii, Herdm. (Med. & Mai.) 



I' ■ 

 D1STOM4, Gcertner, 1774, Sav., 1816. 

 i _ ^ 



Colony massive, sessile or scarcely pedunculated. 



Systems absent or imperfect. 



Ascidiozooids divided into thorax and abdomen, not enclosed 

 in calcareous capsules, and having both apertures 6-lobed and 

 opening directly on to the surface. Thorax aud abdomen often 

 united by a long narrow pedicle. 



Test gelatinous, with no spicules. 



Branchial sac with from 3 to 20 or more rows of stigmata. No 

 internal longitudinal bars. 



Dorsal lamina represented by lauguets. 



Alimentary canal posterior to the branchial sac. 



Gonads placed alongside the intestinal loop. No incubatory 

 pouch present for the embryos. 



The species of Distomama,j be separated thus : — ■ 



[Wall of stomach smooth 1 



[ Stomach-wall not smooth 2 



(Wall of stomach thickened to form a reticulation ; 24 rows of stigmata. 

 B. adriaticum, v. Dr. (Med.) 

 Wall of stomach grooved longitudinally ; 12 rows of stigmata. [Eur.) 

 B. cristallinuvi* , Een. (Med., N.W. 



-, f With only 3 rows of stigmata in branchial sac 3" 



\ With more than 3 rows of sligmata 4 



* B. vifrcum,- Sars, is either this species or closely related to it. 



