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APPENDIX. 



During the course of publication of these volumes many new 

 facts respecting the shells and animals therein described have 

 been brought to light, in a great measure owing to the attention 

 directed to them in consequence of the indications of desiderata 

 mentioned in the preceding pages. Many new localities have 

 also been recorded, and a few new species discovered. The great 

 length to which our work has extended will not warrant our 

 entering upon not a few of the controversial questions that have 

 arisen out of the vigour with which the study of the British Mol- 

 lusca has recently been pursued, and compels us to confine the 

 matter of this Appendix to descriptive notices necessary for the 

 completion of our History. 



TUNIOATA. 



SYNTETHYS. Forbes and Goodsir. 

 (Family Clavelinid.e.) 



Common mass sessile, gelatinous, forming a single orbicular 

 system. Individuals very prominent, arranged subconcentrically. 

 Branchial and anal orifices simple, and not cut into rays. 



Thorax oblong and cylindrical : branchial chamber with thir- 

 teen transverse rows of oblong openings, fringed and ciliated ; 

 hooked fleshy tubercles at the intersections of the branchial 

 meshes. (Esophagus elongated, situated on the left side. Stomach 

 cubical, spongy or glandular. Intestinal loop large and open, 

 reaching to the bottom of the muscular tunic ; its ascending 

 portion glandular, probably hepatic ; the rectum passes from the 

 ventral to the right side of the oesophagus ; the anus is on the 

 dorsal edge of the sac about the middle. The ovary is in the 

 loop of the intestine, but was not in season in the specimens 



