TUNICATA. 



1187 



DICHITONIDA. Family ASCIDIAD^E, E. 

 Forbes. Synonyms : Tethyes simples, Savigny ; 

 Ascididfc, MacLeay ; Tuniciers libres on As- 

 cidienx, Lamarck; Ascidiaria, Stark; " lex Iso- 

 lees" Cuvier ; Ascidiacea, pars, Blainville ; tliis family : 

 Ascidiens simples, Milne Edwards ; Ascidicnx, 

 Van Beneden. 



Body simple, fixed ; animals isolated or 

 gregarious ; not united into groups by a com- 

 mon integument ; oviparous, not gemmipa- 



rous. The following genera are members of 



ASCIDIAD^E, 

 vel 



ASCIDI/E SIMl'MCES 



Branchiae not plicated 



Branchiae plicated - 



Genus Ascidia, Baster and Linnaeus. 

 " Rarely," says Professor E. Forbes, " is the 

 dredge drawn up from any sea bed at all pro- 

 lific in submarine creatures, without contain- 

 ing few or man)' irregularly shaped leathery 

 bodies, fixed to sea-weed, rock, or shell, by 

 one extremity or by one side, free at the 

 other, and presenting two more or less pro- 

 minent orifices, from which, on the slightest 

 pressure, the sea-water is ejected with great 

 force. On the sea shore, when the tide is 

 out, we find similar bodies attached to the 

 under surface of rough stones. They are 

 variously, often splendidly, coloured ; but 

 otherwise are unattractive, or even repulsive, 



Fig. 766. 



Ascidia mammillata. (Original.) 

 a, branchial orifice, open ; b, anal orifice, closed. 



in aspect. These creatures are Ascidia;, pro- 

 perly so called. Numbers of them are often 

 found clustering among tangles, like bunches 

 of some strange semitransparent fruit." Some 

 species (in France, vu/go " le vichet ") on the 



f Sessile 



1 



Pedunculated 



f Ascidia.* 

 " { Molgula. 



f Cynthia. 

 - -J Dendrodoa. 

 [ Chfhosoma. 



(Bo tenia. 

 Cystingia. 

 Bipapillaria. 



coasts of the Channel -j- and the Mediterra- 

 nean, and in the Chinese Seas, are valued as 

 articles of food In this genus (fig. 766.) 

 the body is sessile ; test, coriaceous or gelati- 

 nous ; branchial orifice eight and six-lobed; 

 branchial sac not plicated, surmounted by a 

 circle of simple tentacular filaments. 



Genus Molgtila, E. Forbes ; synonym, As- 

 cidia, Auct. Body more or less globular, 

 attached or free ff ; test membranous, usually 

 invested with extraneous matter ; orifices on 

 very contractile and naked tubes, the bran- 

 chial six-lobed, the anal four-lobed. 



Genus Cynthia, Savigny ; synonym, Ascidia, 

 Auct. Body sessile, fixed or unattached; test 

 coriaceous ; branchial and anal orifices open- 

 ing in four rays or lobes ; branchial sac lon- 

 gitudinally plicated, surmounted by a circle of 

 tentacular filaments. 



Genus Dcndrodoa, MacLeay. Body sub- 

 cylindrical, fixed, sessile ; test coriaceous, 

 smooth ; orifices terminal, minute, indistinctly 

 quadrifid ; branchial sac plicated ; tentacula 



* Some very good observations on the subdi- 

 visions of the Ascidiai have been made by M. Sa- 

 vigny, Dr. Fleming, and Mr. MacLeay. But we 

 must not here enter further into details. The fol- 

 lowing classification is that adopted wholly or iu 

 part by the above authors respectively : 



I Pyrena. 



Phallusiae - - < Phallusia. 

 (_ Cioua. 



ASCIDI - E - 'I f Cynthia. 



I Caesira. 

 Cynthia} - -^ Styela. 



I Pandocia. 

 (_Dcndrodoa. 



) " At Cette," says Van Beneden, " Ascidia are 

 taken regularly to market ; and Cynthia microscomus, 

 although so repulsive externally, furnishes a very 

 delicate morsel, much sought after by some." 



J Individuals of several species of Ascidians, viz. 

 of the following genera, Mokjida, Cynthia, Cystingia, 

 13'ipiipUlaria, and Pelonaia, are found unattached. 

 These animals, however, cannot be said to have an 

 entirely free existence, their tests, whether pe- 

 dmicled or otherwise, being usually more or less 

 imbedded in sand or mud, and frequently held to 

 their anchorage by the agglutination of the sur- 

 rounding sand-grains to their outer surface. But 

 from such a position they are easily disturbed, 

 unless when they are lodged within the mud-filled 

 cavities of old shells and of water- worn stoues, as 

 is the case with the Pdvnaia. 



4c 2 



