TUNICATA. 



1243 



There have been certain organic remains * 

 figured and described as belonging to the 

 Tunicate family, but which (with the exception 

 of the obscure and indeterminate Ischadites 

 Kiznigii) have been found to belong to the 

 family of the Cystidea of Von Buch, closely 

 allied to the crinoidean family of the Radial a. 



At first sight there is considerable resem- 

 blance between many of these cystidean forms 

 and the ascidian genus Boltcnia, the body 

 being globose or subcylindrical and pedun- 

 culated. In the Cystidea there are two more 

 or less terminal orifices, and a third lateral 

 aperture. The whole animal is coated with hex- 

 agonal plates variously ornamented ; the stem, 

 perforated throughout and giving evidence 

 of quinary arrangement. "The mouth," says 

 Von Buch, " is planted in the central part of 

 the upper surface, generally in a moveable 

 proboscis, covered with minute plates ; the 

 anal orifice is small, close to the mouth, per- 

 forating a plate, not surrounded by separate 

 valvules ; and the third aperture, probably 

 the ovarial orifice of the animal, is placed 

 further towards the middle, but almost inva- 

 riably on the upper half of the body on which 

 the mouth is placed. It is round or oval in 

 form, not connected with the mouth, and often 

 covered by a five or six-sided pyramid, which 

 seems to be composed of as many little valves." 



We have introduced this description that 

 we may here point out the general similarity 

 of the external form of these obsolete radiate 

 animals to some of the ascidian group, and 

 that w e may in particular point out the very 

 similar armature of ornamented hexagonal 

 plates present in Che/yosoma, with its valve- 

 surrounded orifices. With regard to the ad- 

 ditional orifices, we have but to lengthen out 

 the oviduct or efferent vessel of the Ancidia, 

 and continue it to the surface, as in the mal- 

 formation noticed and drawn by John Hunter, 

 and a very similar arrangement of parts will 

 apparently exist. 



There are several points of analogy between 

 some forms of Ascidies and of Zoophyta asci- 

 duida (Bowcrbankia, &c.) and the Radlata: 

 into this subject we must not now enter ; we 

 can only allude to the observations of Messrs. 

 Forbes and Goodsir on the Pelonaia (see 

 p. 1239.), and leave the subject open to further 

 investigation. 



BIBLIOGRAPHY. Besides the works, connected 

 with the subject, that are referred to in the text, 

 the following are some of the most important : 

 Peron, Memoire sur le Noveau Genre Pyrosoma. 

 Annales du Museum d' Histoire Naturelle, t. iv. 1804. 

 Lesueur, Memoire sur ^Organisation cles Pyrosonies, 

 et sur la Place qu'ils doivent occuper dans une 

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 Physique, Juin, 1815, t. Ixxx. Desmarest et 

 Lesueur, Me'moire sur le Botrylle etoile (Botnjllus 

 xtdlatus). Lu & la Societe Philomatique de Paris, 

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 t. Ixxx. Desmarest et Lesueur, Extraits de deux 

 MtMiioires lus il la Societe Philomatique de Paris, 

 en Mars et Avril, 1815, sur 1' Organization de deux 



* Leucophthalnms, Kcenig (SphcBi-onitcs), Sa- 

 conites, Uatinesque, &c. 



Animaux Marins place's jusqu'ici dans la Classe des 

 Radiaires, et qui doivent ctre rapporte's a. celles des 

 Mollusques, &c. Bulle'tin de la Socie'te Philoma- 

 tique de Paris, livraison de Mai, 1815. Cuvier, 

 Me'moire sur les Thalides ( Tlialla, Brown), et 

 sur les Biphores (Salpa, Forskaohl). Anuales du 

 Museum d'Histoire Naturelle, t. iv. 1804. Cuvier, 

 Me'moire sur les Ascidies et sur leur Anatomie. 

 Me'moires du Museum d'Histoire Naturelle, t. ii. 

 1815. Chiaje, S. delle, Memoria sulla Storia e 

 Notomia degli Animali senza Vertebre del Regno 

 di Napoli, 4 vols. 4to. Napoli, 18231829. Ibid. 

 Figure, 4to. 18221828. Savigny, J. C., Me'- 

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 MOLLUSCS. Quay et Gaimard, Voyage de 1'Astro- 

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 Naturelles, art Mollusques. Chamis-o, Dissertatio 

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 nye i habet bed den Bergenske Kyst lebende dyr 

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 nelidernes og Molluskernes Classer, 4to. Bergen, 

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 (SalpeB~). Dalzell, A singular Mode of Propagation 

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 Edinb. New Philos. Journ. vol. xxvi. 1839; and 

 Isis, viii. 1839. Dalzell, On some of the rai'er 

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 (Salpa). 4to. London, 1814. Cams, Beitrage zur 

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 lungs Geschichte der Ascidien. Nov. Act. Nat. 

 Cur. vol. x. Gurus, Beitrage zur Anatomie und 

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 Physiol. B. ii. H. iv. Cams, Anatomie Compar. vol. 

 ii. Eysenhardt, Ueber einige merkwurdige Lebens- 

 erscheinungen an Ascidien. Nov. Act. Nat. Cur. 

 t. xi. Lister, Phil. Trans. 1834, part ii. Milne Ed- 

 wards, Observations sur les Ascidies Compose'es, qui 

 se trouvent aux Cote's de la Manche. Me'm. Acad. des 

 Sciences, t. xviii. Milne Edwards, Sur la Circula- 

 tion du Sang chez les Pyrosomes. Comptes Rendus 

 de 1'Acad. des Sciences, t. x. 1840, p. 284. ; Sur la 

 Circulation et sur 1'Existence d'un Systemes Ner- 

 veux chez les Salpes. Ibid. p. 408. Annales 

 des Sc. Nat. 2de series, t. xiii. Milne Edwards, 

 Recherches Zoolog. faites pendant 1111 Voyage eu 

 Sicile. Comptes Rendus, 1844, t. xix. p. 1137. Milne 

 Edwards et Audouin, Re'sume' des Recherches 

 faites aux lies Chaussey. Ann. Sc. Nat. t. xv. 

 Gervais, Suppl. Diet. Sc. Nat. line vol. art. ASCI- 

 DIES. Coste, Recherches sur 1'Appareil respira- 

 toire des Ascidiens. Comptes Rendus, 1842, t. xiv. 

 Broderip and Soicerby, Observations on New Mol- 

 lusca, &c. (C/ielyosoina) Zoolog. Journal, vol. v. 

 Johnson, Mag. Nat. Hist. 1834 (Aplidium). Penny 

 Cyclopedia, articles SALPACEA and TUNICATA. Van 

 Beneden, Recherches sur 1' Embryogenie, 1'Ana- 

 tomie, et la Physiologic des Ascidies Simples. 

 Me'moires de 1' Academic Royal de Belgique, t. xx. 

 1847. Forbes (E ), Forbes and Hanley's History of 

 British Mollusca, 8vo. London, parts i. and ii. 1848. 



(jr. Rupert Jones.) 



