Didemnidæ, Uiaid. 



Didemnoides. (Dmsche 1883). Nov. nom. Lahille 



1890. 



Drasche skiller raelleni ,,tynde" og ,.t}"kke" cormi af 

 slægten Icptoclinum og bibeholder dette navn for de første, 

 medens han kakler de tykke didemnoides. en subdeling ana- 

 log med botrylloides og sarcobotrylloides. At lienytte tyk- 

 kelsen som eneste karaktermerke synes her endnii mindre 

 begrundet end ved botryllidae, da forskjellen er endnu min- 

 dre udpræget. Lahille derimod anvender dette navn for 

 ,,didemnider uden kalkspicula i tunicaen, og hvis bran- 

 chialsæk har 3 rækker stigmata", hvilken sidste navnanven- 

 delse jeg har fulgt, da spiclernes tilstedeværelse eller fra- 

 værelse i tunicaen frembvder en langt constantere karakter. 



Didemnoides variabile, n. sp. 



(Tall. I, fig. 1, -Jj. 



Kolonierne danner cylinderformige eller ganske uregel- 

 mæssige klumper paa indtil 3 cm. længde og 1 cm. tykkelse 

 incrusterende forskjellige alger; .sjeldnere optræder de som 

 skorpeformigc betræk af omtr. 2""" tykkelse og indtiljlO cm. 

 længde almindelig over laminariestilke. 



Farven er lyst graablaa. gran- eller brunagtig. Det 

 mørke pigment, der betinger koloniens farve, er beliggende 

 kun i den abdominale del af individernes ectoderm og skinner 

 ofte gjennem den fa41es tunica som moi'ke punkter. Un- 

 dertiden mangler det morke pigment fuldstændig. Tunicaen 

 er transparent, farveløs og oftest fast, undertiden af en 

 blødere gelatinos konsistens; cellerne er store og blærefor- 

 mige. Kalkspicler mangler fuldstændig. 



Individerne er lysebrune af farve; længden omtr. 2""". 

 De sidder tæt ved hinanden ofte stillede i længere eller 

 kortere rækker. 



In- og egestionsaabningens tuber af samme vidde og 

 længde. Den sidste danner en cyliuderformig tragt. 



Didemnidæ, Oiard. 



Didemnoides. (Dra.sche, l.S83) Nov. nom. Lahille, 



1890. 



Drasche distinguishes between ,,thin" atul ..tliick-' 

 cormi of the genus Leptoclinum and retains tiiat name 

 for the former, calling the thick ones Didemnoides, a sub- 

 divisiou analogous to Botrylloides and yarcobotrylloides. 

 To employ the thickness as the only character mark, seems 

 to have even less ground here than in the Botryllidæ, as 

 the diftereuce is even less marked. Lahille, on the other 

 hand, applies this name to „Didemnidæ without calcareous 

 spicules in the tunic, and whose branchial sac has 3 rows 

 of stigmata." I have followed the latter nomenclature, as 

 the presence or absence of spicules in the tunic presents 

 a far more constant character. 



Didemnoides variabile, n. sp. 



(Fl. I. figs. 1, 2). 



The colonies are in the form of cylindrical or quite 

 irregular lumps up to 3 cm. in length and 1 cm. thick, in- 

 vesting various algæ; thoy appear less frequently as a crust- 

 like investment about 2""" thick and -vvith a maximum length 

 of 10 cm., usually upon Laminaria stalks. 



The colour is either a light bluish grey, greenish or 

 brownish. The dark pigment that dctermines tlie colour 

 of the colony. is only fouiid in tlie abdominal portion of 

 the pctoderm of the individual animals, and often shows 

 through the comraon tunic as dark spots. Sometimes the 

 dark pigment is completely wanting. The tunic is trans- 

 parent, colourless and most frequently firm, though occa- 

 sionally of a softer. gelatinous consistency: the cells are 

 large and bladder-like. Calcareous spicules are entirely 

 absent. 



The members are of a light brown colour, their length 

 being about 2""". They lie close to one another, often 

 arranged in long or short rows. 



The siphons of the branchial and atrial orifices ar& 

 of the same length and breadth. The atrial aperture is 

 in the form of a cvlindrical funnel. 



