398 
EDWIN S. GOODRICH. 
somewhat ill-defined group known as the Archiannelida. 
Under the impression that it was quite a new form, I was on 
the point of issuing this account of its habits and structure 
when I discovered that M. de Beauchamp had last year begun 
to publish a description of this very animal in the ‘Bull. 
Scient. de la France et de la Belgique* ( 2). 1 It appears to be no 
other than the Ner ilia antennata, so named by 0. Schmidt 
in 1848 ( 21 ), and hitherto considered as an aberrant Poly- 
chaete. Since then de Quatrefages ( 16 ) and Claparede ( 3 ) 
have written about it, and Miss Pereyaslawzewa ( 13 ) pub- 
lished a long account of its anatomy, which (as already 
pointed out by de Beauchamp) is neither complete nor 
correct. To M. de Beauchamp belongs the credit of having 
begun the first accurate account of Nerilla, and of having- 
first pointed out its resemblances to Protodrilus. 
General Appearance and Habits. 
Nerilla antennata is a very small creature, full-grown 
specimens being about 1'5 mm. in length. The sexes are 
separate and of similar size and outward shape. The body is 
nearly colourless and transparent, with, however, some 
brownish epidermal pigment in the head and a greenish- 
brown tinge towards the middle, due to the presence of 
granules in the wall of the alimentary canal. When mature 
the ripe spermatozoa, or ova, give an opaque, white appear- 
ance to the hinder region of the body. 
The worms were found in large numbers in the tank, 
apparently spending most of their life at the bottom, in the 
mud chiefly composed of diatoms and other algae. These 
plants form their exclusive diet. When undisturbed the 
Nerilla creeps about a flat surface, moving by means 
of the ciliated ventral groove which extends along the 
1 I immediately wrote to M. de Beauchamp, who courteously urged 
me to publish my observations, as his own are still incomplete and 
unlikely to be finished for some time. With bis approval, then, this 
paper is published, giving for the sake of completeness a full descrip- 
tion of my results with very little alteration. 
