salfokl (tab. V, fig. 1) og store papiller i gjællesækken, 

 som har 3 tværribber af 2(len orden mellem 2 af Iste, alt- 

 saa ganske som de typiske .4sc?V??'« -arter. Herdman anfører, 

 at gjællesækken mangler den almindelige fine foldning, som 

 findes hos de typiske former saavel af Ase/dia som Asci- 

 diellcL Hos de af mig undersogte exemplarer var dog 

 ayællesækken fint foldet, oraend denne foldning ikke var saa 

 stærk som almindelig. Som ovenfor nævnt taler kun nerve- 

 gann^liets beliggenhed for denne arts slægtskab med Asd- 

 diélla : dette afsvæ^kkes dog ganske, naar man tager hensyn 

 til, hvor varialtelt dette forhold er hos Ascidia. Hos vore 

 øvrige arter af denne slægt er afstandcn iio.s compJanata, 

 Falir. ca. V«n ^^ kroppens længde (0.:> mm. hos et 29 mm. 

 hoit ex.), hos rjelatinosa, Kiær og longimplioinda, Kiær 

 */io— \i2> lios ronchilegd, 0. F. Miill. Ve og endelig hos 

 menhdci, Lin. endnu mere. Hvis efter dette en grændse 

 skulde trækkes, maatte det nærmest ske mellem coniplanata 

 og gelatinosa ; dog er romplanata efter sin hele øvrige byg- 

 ning en ægte Ascidia. Da de ovrige karakterer, Roule 

 opstiller for Ascidiella, ogsaa varierer stærkt, l)liver en 

 grændse mellem de to slægter umulig at trække og vil altid 

 blive unaturlig. Uagtet jeg derfor tror, at Roules slægt 

 neppe kan opretholdes, har jeg forelobig beholdt den, nær- 

 mest som en subgenus, for en gruppe meget nærstaaende 

 former, der udraærker sig ved følgende 3 karakterer: 



1. Nervegangliet næsten direkte over tlimregrulien. 



2. Dorsalfolden standser ved svælget. 



3. Papillerne i gjællesækken ganske eller næsten fuldstæn- 

 digt reducerede. 



Alle vore Ascidiella-txvtev er nær beslægtede. .4. rir- 

 ginea, 0. F. Miill. maa ansees som distinkt art; A. jMtida, 

 0. F. Miill. staar derimod asimsa, 0. F. Miill. saa nær, 

 at dens berettigelse maaske er tvivlsom. A. luiuuta, Kiær 

 og expansa, Kiær er ligeledes meget nær beslægtede med 

 aspersa; men da jeg ikke har havt anledning til fornyet 

 undersøgelse af dem, kan jeg endnu ikke afgjore, hvorvidt 

 deres foreløbige opstillelse som nye arter er berettiget 

 eller ikke. 



2. Ascidiella virginea, 0. F. Midl. 

 Herdman, Notes on British Tunicata, H, pag. 432, 440. 

 Traustedt, Ascidiæ simplices, ,,Hauch" V. 



Udbredelse: Fundet et par steder ved sydkysten og 

 vestlandet; ikke almindelig, mest paa sandbund, 25 — 100 m. 



a specinen measuring 50 mm. in height (Pl. V., fig. 2). 

 On the otiier hand. reiiosa has a very long post-buccal 

 dorsal lamina (Pl. V, fig. 1), and large papillæ in the 

 branchial sac. which has 3 transverse bars of the second 

 order between 2 of the first, being thus exactly like the 

 typical Ascidia species. Herdman states that the branchial 

 sac is without the usual fine folds which are found in tlie 

 typical forms liotli of Ascidia and Ascidiella. In the spe- 

 cimens examined by me, however, the branchial sac was 

 finely folded, although this folding was not so marked as 

 usual. As already mentioned, the position of the nerve- 

 ganglion is the only iudication of the relation of this species 

 to Ascidiella; but this is altogether weakened when the 

 variableness of that position in Ascidia is tåken into con- 

 sideration. Of the other Norwegian species of this genus, 

 the distance in compjlanafa. Fabr.. is about '/'so of the length 

 of the body (0..'i mm. in a 29 mm. high specimen) in gela- 

 tinosa, Kjær, and loiigisiplionafa, Kjær, i/j(, to ^u'- in coh- 

 chilega. 0. F. Miill. Vu, and lastly. in merduhi, Lin., still 

 more. If, from this. a limit had to be drawn. it ought 

 properly to be between complanaUi and gelafiiinsn. although 

 complaiiuta. judging from its structure in all otlier respects, 

 is a true Ascidia. As the remaining characters given by 

 Roule for Ascidiella, also vary considei'ably. it will be im- 

 possible and always unnatural to draw a boundary-line 

 between the two genera. Notwithstanding my belief that 

 Roule's genus can scarcely be maintained. I have for the 

 l)resent retained it, more imniediately as a suli-genus, for 

 a group of very nearly allied forms that are distinguished 

 by the 3 following characters: 



1. The nerve-ganglion is almost directly above tlie dorsal 

 tubercle. 



2. Tlie dorsal lamina stops at the oesophagus. 



3. The papilLæ in the branciiial sac are entirely or al- 

 most entirely reduced. 



All tiie Norwegian species of Ascidiella are ne.irly 

 related. ^4. lirginea, O. F. Miill. must be regarded as a 

 distinct species. A. patnla, 0. F. Miill.. on tlie other iiand, 

 is so nearly allied to aspersa, O. F. Miill., tliat its legi- 

 timacy is perhaps doubtful. A. mimtfa, Kiær, and expansa, 

 Kiær, are also very nearly related to aspersa: liut as I 

 have had no opportunity for renewcd exaniination of tliem, 

 I cannot yet determine how far their temporary classifi- 

 cation as new species is justified. 



2. Ascidiella virginea, 0. F. Miill. 

 Herdman. Notes on British Tunicata, II, pp. 432. 440. 

 Traustedt, Ascidia simplices. ..Hauch" V. 



Distribution. Found in a few places on the south 

 and west coasts; not common. generally on sandy bottom, 

 depths of from 25 to 10( i m. 



