12 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 122 



them unreliable. The danger of eniploymg these superficial charac- 

 ters is multiplied further by the existence of animals essentially 

 indistinguishable from V. pavida but closely approaching V. mulleri in 

 some respects. Braem (1951, p. 45) has erected a new species and 

 genus, Bulbella abscondita, to include them. The species occurs only 

 where both V. pavida and V. miilleri are common. 



With regard to item 1 above, Braem (1951, p. 23) himself points 

 out that the position of the "sitzenden Sphinkter" [fixed sphincter] is 

 the most "wesentlich und konstant" [fundamental and constant] 

 feature distinguishing Victorella from Tanganella, yet he states: 

 "Die Lage des sitzenden Sphinkter ist nicht immer ganz gleich, da die 

 benachbarten Darmteile einigermasser gegeneinander verschiebar 

 sind" [The position of the fixed sphincter is not always entirely the 

 same since the neighboring parts of the gut are somewhat displaceable 

 against one another] (loc. cit.) . A glance at his figures (plate II : fig. 9 

 and plate V : fig. 5C) is enough to convince a reader that the overlap 

 is considerable. The situation in V. argilla, with its diffuse system of 

 muscle bands around the entire distal portion of the gut, appears to 

 cast doubt on the validity of this character among ctenostomes; 

 nevertheless, if characters of this nature should prove reliable, then 

 the position of the sphincter in form A of V. argilla would seem to ally 

 it more to V. pavida (and Bidbella abscondita?) than to V. {= Tan- 

 ganella) miilleri. 



As regards items 2 and 3 above, V. argilla further resembles V. 

 pavida in the possession of an intertentacular organ (lacking in V. 

 miilleri). Unfortunately, little is known of the reproductive habits of 

 V. argilla (see p. 9). 



It is obvious that the systematics of Victorella and its relatives is 

 unstable and that much of the confusion has arisen from an un- 

 certainty as to what characters are of importance. Since it is not at 

 all clear what the limits of the genera (or even of the species) should 

 be, I am exceedingly hesitant to further confound the already perplex- 

 ing taxonomy by inserting yet another genus into the literature. 

 Therefore, even though the differences between V. argilla and other 

 Victorella are greater than those between most other genera in its 

 family (between Victorella and Sundanella or Bulbella and Tanganella, 

 e.g.), I place it in the genus Victorella as defined by Prenant and Bobin 

 (1956, p. 139). It should be distinguished from all other members of 

 the genus by the following characters: (1) the possession of filiform 

 processes that secrete an adhesive that causes them to be invested in a 

 coat of foreign material; (2) the disposition of the apertural muscles 

 into a radial or bilaterally paired configuration (the aperature of the 

 retracted zooid is therefore not quadrangidar) ; (3) the marine habitat 

 of T'^. argilla. All other described forms are known only from brackish 



