JULES-CESAR SAVIGNY. 571 



4. Section. Branchial aperture only with six regular rays. 



8. SYNOICUM. Body pedunculated, cylindrical, vertical ; 



a single system. 



9. APLIDIUM. Body sessile, multiform ; systems without 



central cavities. 



10. POLYCLINUM. Body sessile, multiform ; systems with 



central cavities. 



11. DIDEMNUM. Body sessile, fungous, crustaceous ; sys- 



tems without central cavities. 



5. Section. Apertures without rays. 



12. Euc(ELiUM. Body crustaceous ; systems without cen- 



tral cavities. 



13. BOTRYLLUS. Body crustaceous ; systems with central 



cavities. 



2. Family LUCLE. 



Body floating. Apertures exactly opposite, and communicating by the 

 cavity of the branchiae. Branchial cavity open at both ends, the superior 

 aperture without tentacular filaments, but margined with a denticulated ring. 

 Branchiae disjunct. 



I. Simple Lucise. 

 II. Compound Lucise. 



14. PYROSOMA. Body in form of a tube closed at one ex- 



tremity ; a single system. 



Order II. ASCIDI^ THALIDES. 



Cloak adherent everywhere to the envelop. Branchia unequal, narrow, 

 consisting of two leaflets attached to the anterior wall, and to the posterior 

 wall of the respiratory cavity. Branchial aperture furnished with a valve. 

 Obs. Savigny did not classify this Order. 



