§ 171. THE ACEPHALA. 187 



Vogt. Anatomie der Lingula anatina. Ibid. VII. 184.3, p. 1, Taf. I. II. 



Van Beneden. Memoire sur TEinbryogenie, TAnatoinie et la Physiologie 

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

 XIII. No. 2. 



ADDITIONAL BIBLIOGRAPHY. 



Kolliker. Ueber das Vorkom. d. Holzfas. im Thierreich., in the Ann. d. 

 Sc. Nat. 1846, p. 19.3, PI. V.-VII. 



Van Beneden. Recherches sur 1' Embryogenie, TAnatomie, etla Physi- 

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

 1847. 



Frey and Leuckart. Beitragen zur Kenntniss der wirbellosen Thicrc 

 mit besonderer Berucksichtigung der Fauna des Norddentschen Meeres. 

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



Deshayes. Exploration scientifique de I'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 MoUusca 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 MoUusca acephala, Oversigt af k. Vet. 

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

 or, its translation in Muller's Arch. 1848, p. 531 ; or, in Wiegviann's Kxch. 

 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. Beitriige zur Anatomie und Physiologie der Weich- 

 theire, Konigsberg, 1851. [Devoted to the nervous, circulatory, and res- 

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



CHAPTER I 



CUTANEOUS SYSTEM. 



§ in- 



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 Lamellibranclna, and Brachiopoda, 

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



• The mantle is leathery with Cynthia, cartilagi- soft with Snlpa, and f^clatinous with Clavelina, Di- 

 nous and hard with Pkailusia, cartilaginous and azona, ApUdium, Botrijllus, and Pyrosoma. 



