^ 171. THE ACEPHALA. 187 



Vogt. Anatomie der Lingula anatina. Ibid. VII. 1843, p. 1, Taf. I. IT. 



Van Beneden. Memoire sur l'Embryogenie, rAnatomie et la Physiologie 

 des Ascidies simples, &c., in the Bullet, de l'Acad. royale de Belgique, 

 XIII. No. 2. 



ADDITIONAL BIBLIOGRAPHY. 



Kölliker. Ueber das Vorkom. d. Holzfas. im Thierrelch., in the Ann. d. 

 Sc. Nat. 1846, p. 193, PL V.-VII. 



Van Beneden. Recherches sur l'Embryogenie, l'Anatomie, etla Physi- 

 ologie des Ascidies simples, in the Mem. de l'Acad. Roy. de Belgique, XX. 

 1847. 



Frey and Leiickart. Beiträgen zur Kenntniss der wirbellosen Thiera 

 mit besonderer Berücksichtigung der Fauna des Norddeutschen Meeres. 

 Braunschweig, 1847, p. 46, Anatomie des Pfahlwurmes {Teredo navalis). 



Deshayes. Exploration scientifique de l'Algerie, pendant les annees 

 1840, 1841, 1842. Histoire naturelle des Mollusques, avec un Atlas de 

 117 Planches. Paris, 1847. 



Ed. Forbes and Hanley. A History of British Mollusca and their 

 Shells. 4 vol. London, 1853. [Contains many anatomical details.] 



Dalyell, T. G. Rare and remarkable animals of Scotland, represented 

 from living subjects, with practical observations on their nature. Vol. II. 

 London, 1848, p. 138-173, PI. XXXIV.-XLIII. (Ascidiae). 



Loven. Om utvecklingen af Mollusca acephala, Oversigt af k. Vet. 

 Akad. Forhandl. 5te Argängen, Dec. 1848. Stockholm, 1849, p. 233-257 ; 

 or, its translation in Miiller's Arch. 1848, p. 531 ; or, in Wiegmann' s Arch. 

 1849, p. 312. 



Quatrefages. Memoire sur le Genre Taret (Teredo Lin.), in the Ann. 

 d. Sc. Nat. XI. 1849, p. 19. 



Memoire sur I'embryogenie des Tarets. Ibid. p. 102. 



T. Rupert Jones. Cyclop. Anat. and Physiol. IV. p. 1185, Art. Tuni- 

 cata. 



G. A. F. Keber. Beiträge zur Anatomie und Physiologie der Weieh- 

 theire, Königsberg, 1851. [Devoted to the nervous, circulatory, and tq^-, 

 piratory systems of the fresh-water Bivalvia.] — Ed. 



CHAPTER I. 



CUTANEOUS SYSTEJVr. 



§ m. 



The body of the Acephala is enveloped in a special mantle, whicH, with the 

 Tunicata, is composed of a leathery, cartilaginous, or gelatinous substance, 

 scarcely at all irritable. ^^' But with the Lamellibranchia, and Brachiopoda, 

 it is composed of a contractile, fleshy membrane. With the Tunicata, it com- 



1 The mafitl? is leathery with Cynthia, cartilagi- soft with Salpa, and gelatinous with davelina, Di 

 taus and hard with Phallusia, cartilaginous and azona, Aplidium, Botryllus, and Pyrosoma, 



