§ 171. ■ THE ACEPHALA. 187 



Vogt. Anatomie der Llngula anatina. Ibid. VII. 1843, p. 1, Taf. I. II. 



Van Beneden. Memoire sur I'Embryogenie, TAnatomie et la Physiologie 

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

 XIII. No. 2. 



ADDITIONAL B I B L I G il A P H Y . 



KolUker. Ueber das Vorkom. d. Holzfas. im Thierreich., in the x\nn. d. 

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



Vmi Beneden. Recherclies sur I'Embryogenie, IMnatomie, etla Physi- 

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

 1847. 



Frey and Leuckart. Beitriigen zur Kenntniss der wirbellosen Thierc 

 mit besonderer Berucksichtigung der Fauna des Norddentschen Meeres. 

 Braunschweig, 1847, p. 46, Anatomic 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 Mollusca and their 

 vShells. 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. (Aseidiae). 



Loven. Om utvecklingen af Mollusca aeephala, Oversigt af k. Yet. 

 Akad. F6rhandl. 5te Argangen, Dec. 1848. Stockholm, 1849, p. 233-257 ; 

 or, its translation in Mvller's Arch. 1848, p. 531 ; or, in Wiegmajin's Arch. 

 1849, p. 812. 



Quatrefas^es. Memoire sur le Genre Taret [Teredo Lin.), in the Ann. 

 d. Se. Nat. XL 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. Beitragc 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. 



§ 171. 



The body of the Aeephala 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 mantle is leathery with Cynthia, cartilagi- soft with Salpa, and gelatinous with Clavelina, Di- 

 nous and hard with Phallusia, cartilaginous and azona, Jplidium, Botryllus, and Pijrosoma. 



