468 MOLLUSCA. TUNICATA. Pandocia, 



Gen. CXLIV. PANDOCIA. — Ovarium single, and situate in 

 the fold of the intestine, the latter strengthened by a cy- 

 lindrical rib from the pylorus to the anus. 



586. P. concMlega. — Cylindrical or oval_, wrinkled, subdia- 

 phanous, and generally covered Avith the fragments of shells. 



Ascidia conch. Mull. Zool. Dan. t. 34. f. 4, 5, 6. Stewart's El. i. 392 — 

 p. mytiligera, Savigny^ Mem. ii. 158. t. viii. f. 2— On different parts 

 of the Scottish coast, common. 

 Length upwards of an inch, the breadth about one-third less ; orifices lit- 

 tle raised, and rather remote ; the inner tunic bluish-white ; tentacular fila- 

 ments of the branchial orifice, long, slender, and upwards of twenty in num- 

 ber. The Modiolus discors is frequently found imbedded in the integument. 



Gen. CXLV. CLAVELLINA.— Branchial and anal orifices 

 Avithout rays ; the angles of the branchial meshes simple ; 

 the intestine destitute of a rib. 



587. C. lepadiform'ts. — Body transparent, exhibiting the dark 

 coloured branchial sac, intestine and stomach. 



Ascidia lep. Mull. Zool. Dan. t.lxxix. f. 5. — C. lep. Sav. Mem. ii. 174, 



and 237 Not common, adhering to sea-weeds. 



Length about two inches ; thick at the base, where the stomach is placed ; 

 narrow during the course of the intestine, and then expanding into a blunt 

 head for the branchial cavity ; at the base there are numerous branched tubes, 

 with a central medullary line. Dr Leach communicated this species, from 

 the British seas, to M. Savigny in 1816. I have obtained it by dredging in 

 Kirkwall bay, Orkney. 



Gen. CXLVI. PIRENA.— The branchial sac as extended 

 as the tunic ; stomach not resting on the intestine. 



588. P. prunwn. — Ovate, smooth, greenish, and diaphanous- 



Ascidia prunum, Mull. Zool. Dan. t. xxxiv. f, 1, 2, 3. Stewart's El. i. 



392 Adhering to fuci, not common. 



Upwards of an inch in diameter ; inner tunic white, the orifices with 7 or 

 8 red lines. 



Gen. CXLVII. CIONA. — Branchial sac shorter than the 

 tunic, and exceeded by the viscera. 



589- C. intestinalis. — Lengthened, bifid at the extremity ; 

 grey, with the orifices yellow. 



Ascidia int. Linn. Syst. i. 108?. Ellis's Zooph. 49 — A. corrugata. Mull. 



ZooL Dan. t. Ixxix. f. 3, 4 Adheres to fuci beyond low water-mark. 



Length about two inches ; thickest at the base, where it adheres by nu- 

 merouJ5 coarse threads, soft and transparent ; the orifices are approximate. 



