Genus 7. ANCULA,* Loven. 



Corpus elongating gracile, lseve, non palliatum. Caput terminate, subinferius, utrinque in 

 papillam brevem tentaculiformem productum. Tentacula dorsalia 2, subclavata, laminata, non-re- 

 tractilia, basi stylis instructa. Branchiae plumosse, in lineal media dorsi anum circumdantes ; cirris 

 linearibus, subclavatis, utrinque o-rnatse. Apertura genitalis ad latus dextrum. 



Like others of the Poly cerium , this genus is founded on a single species, and we may 

 therefore refer to the account of that species itself for some part of its history. Ancula was 

 established by Professor Loven in. his excellent little 'Index Molluscorum Scandinaviae,' 

 published in 1846. The species was first described by one of the authors of this work in 

 1841. f We have recently learned, however, that this beautiful little mollusk had been dis- 

 covered by Dr. Fleming so long ago as 1814, having ascertained from a sketch kindly sent us 

 by that distinguished naturalist, that the animal referred to in his ' British Animals, 5 page 

 283, is no other than the Ancula cristata. 



The genus differs from Polycera in having basal filaments to the tentacles, and in the 

 absence of a velar expansion and dorsal area. These latter circumstances likewise separate it 

 from Idalia, with which, in most of its characters, it very nearly agrees ; though its general habit, 

 and more slender and graceful form, serve at first sight to distinguish it. The single repre- 

 sentative of this genus appears to be generally diffused throughout the seas of Northern 

 Europe, and is plentiful on many parts of the British coast. We have not heard of its occur- 

 rence in more southern latitudes. It is probably carnivorous, as it is never found on sea- 

 weeds, but is most plentiful on stones, associated with minute zoophytes. 



Ancula has the body elongated, slender, and smooth, terminating in a point behind. 

 There is no indication of a cloak, with the exception of a slight ridge in the vicinity of 

 the gills, on which the branchial appendages are placed. The head is terminal, and without 

 veil, having its sides produced into two short tentacular processes. The mouth is not 

 provided with corneous jaws, but has a spinous prehensile collar. There are two subclavate, 

 strongly laminated dorsal tentacles, without sheaths and non-retractile ; near the base they 

 are each furnished with two styliform appendages. The branchiae are plumose, placed round 

 the vent, on the most elevated part of the back, on the central line ; they are surrounded by 

 numerous linear or subclavate processes. The foot is slender and nearly linear. The com- 

 mon aperture of the genital organs is placed pretty far forward on the right side. 



Any description of the anatomy of so minute and delicate an animal as Ancula must 

 necessarily be imperfect ; we have, however, possessed the advantage of having had at our 

 command a large supply of specimens, and being thus fortunate, we have succeeded in 



* Ancula, a maid servant. f Ann. Nat. Hist., v. 6, p. 340. 



