A Description of three Acoela from the Gulf of Naples. 
293 
Various stains were employed, among them Apathy's Haematein 1. A, 
Good results were obtained by combining Delafield's Haematoxylin 
with either Orange G, or Eosin. The former combination stained the 
reproductive cells purple. the glands blue, and the parenchyma a Hght 
yellow. Glandulär structures were also brought out well by using a 
triple stain consisting of equal parts of Methyl green, Acid fuchsin, and 
Orange G. 
B. Description. 
1. Äphanostoma pulcJiella (Uljanin, non Ä. pulchella mihi, Pereyas- 
lawzewa). 
a) Historical review. 
More than forty years ago Uljanin (1869) included under the gene- 
rie name Nadina several species of small worms found in the Bay of 
Sebastopol. According to his Classification, the genus Nadina includes 
Aphanostomidae without a pharynx, with mouth opening on the ^^entral 
surface behind the otolith, two eyes, and a bursa with no hard parts. 
Ludwig von Graff (1886) first pointed out that the position of this 
genus was not definitely determined, for if there are two genital openings 
present Nadina belongs between Äphanostoma, and Convoluta; but if 
there is only one opening, it is intermediate between Proporus and 
Convoluta. 
Nadina pulchella, which is, no doubt, the same species that occurs 
at Naples, is described by Uljanin as pear-shaped, yeUow in color, with 
many small rhabdites arranged in diagonal rows upon the surface 
of the body. The length according to his measurements, varies from 
0,48 mm to 0,5 mm. In the region of the mouth and statocyst he ob- 
served a mass of dark "pigment" which he interpreted as "diffuse eyes". 
He also mentions the oil globules in the same region. The position of 
the ovaries is lateral, and in the center he observed a large round organ 
which he called a bursa seminahs and lying near it an egg-shaped bladder 
(Hode). The spermatozoa he represents with large heads and slender 
tails. 
Some years later Pereyaslawzewa (1892) in her Monograph on 
the Turbellaria of the Black Sea, gave a detailed account of a worm 
which she caUed Äphanostoma pulchella mihi, and which she seemed 
to consider the same worm that Uljanin named Nadina pulchella. 
Pereyaslawzewa describes this species as small, lively, and easy to 
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