294 
Florence Peebles. 
distinguisi! on account of its size and apple-green color. The otolith 
is in the usuai place, but no eyes are present; the body is covered 
with ciha. She recognizes that "pigment granules" first described by 
Uljanin, are not pigment at ali, but are the granules of concrement, so 
often found in the Acoela. These granules appear black on account of 
their opacity. Much attention is given by this investigator to the pha- 
rynx whose structure she considers pecuhar to this form. Two types 
of pharynx bave been distinguished by von Graff, the "pharynx sim- 
plex", and the "pharynx compositus"; the latter type is divided into 
two kinds the "bulbosus" and the "pHcatus". The pharynx of Convo- 
luta belongs to the simplex type, but that of Äphanostoma pulchella mihi, 
according to Pereyaslawzewa, is bulbose. She describes it as formed 
of two superimposed tubes "qui sont liés par leurs ouvertures; il ne reste 
une space hbre entre leurs parois formée de plusieurs couches de fibres 
musculaires tres fins. Le vide est traversé par de nombreux filaments 
musculaires très fins". These fibres are perpendicular to the surface. 
The outer layer of muscle cells is much more distinct than those composing 
the inner layer. These finer structures are however not clearly repre- 
sented in her figures. 
When VON Graff examined the various species of Acoela from the 
Black Sea (1904) he found neither the species described by Uljanin, 
nor that of Pereyaslaw^zewa. He cahs attention (p. 222) to the fact 
that nothing is said by either author about the number of genital openings, 
neither is there any accurate statement in regard to the presence of a 
chitinous mouth-piece on the bursa, and these two points must be clearly 
estabhshed before any definite conclusions are drawn. 
The species that I found at Naples resembles that of Uljanin's 
description so closely that I feel justified in identifying it as Äphanostoma 
pulchella. The generic name Äphanostoma must be given because the 
bursa seminalis has no chitinous mouth-piece, and there are two genital 
openings (fig. 4). The only point of divergence from the description of 
Uljanin is in the shape of the mouth which he represents as slit-hke 
instead of round, and he does not seem to bave observed the pharynx. 
As we bave only one "Habitusbild" by Uljanin, it is perfectly possible 
that the pharynx was overlooked by him. 
b) External features, and behaviour. 
The body of Äphanostoma pulchella is pear-shaped, the broad anterior 
end measuring about 0,2 mm in diameter, the posterior end tapering to 
a blunt point (pi. 10, fig. 2). The entire worm never exceeds 0,5 mm 
