ME. MACDONALD ON A NEW GENTT9 OF TUNICATA. 81 



The heart (fig. 3 d) lay in front of the stomach, extending 

 into the interval between that organ and the oesophagus. 



The follicles of the testicle skirted the convexity of the intes- 

 tinal curve, and immediately superficial to these were the sacculi 

 of the ovarium. The ducts, however, converged from the hollow of 

 the intestinal loop, and led forwards beside the rectum (fig. 3 c) . 



Peropkora is a pouch-bearer ; but the present genus, being a 

 little pouch in itself, may be called Pera ; and the species Huxleyi, 

 after one who, above all English observers, has added most to our 

 precise knowledge of the Tunicata. 



The original specimen from which this imperfect description 

 was taken is now in the possession of Professor Huxley ; and I 

 may mention, in conclusion, that Professor Claparede suggested to 

 me the existence of a similar operculate condition of the test in 

 the case of the so-called house of Appendicularia, in which, how- 

 eyer, I believe each aperture is furnished with a distinct valve. 



KEFERENCES TO THE FI (HIKES. 



1. Front view of the animal with the lid closed. 



2. Side view of ditto (nat. size). 



3. Posterior view magnified, with a portion of the test removed 

 to show the internal organs. 



a. Mantle detached from the test below. 



b. Stomach. 



c. Intestine. 



d. Heart. 



e. Testicular follicles. 



f. Ovarium. 



g. Ducts. 



4. Front view magnified, with the operculum thrown open. 



a. Operculum. 



b. Body of the cell. 



c. Conjunctive membrane. 



d. Branchial orifice with tentacula appearing. 



e. Cloacal orifice. 



f. Occlusor muscular fibres. 



Fig. 

 Fig. 

 Fig. 



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LINN. PROC. — ZOOLOGY, VOL. VI. 



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