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. conchilega . — Cylindrical or oval, wrinkled, subdia- 
phanous, and generally covered with 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 
without rays ; the angles of the branchial meshes simple ; 
the intestine destitute of a rib. 
587. C. lepadiformiis . — 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, 
Avith 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. 'prunum. — 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. CXLVI I. CIONA. — ^Branchial sac shorter than the 
tunic, and exceeded by the viscera. 
589. C. mtestinalis. — Lengthened, bifid at the extremity ; 
grey, with the orifices yellow. 
Ascidia int. Linn. Syst. i. 1087. 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- 
merous coarse threads, soft and transparent ; the orifices are approximate, 
