TUKBELLARIA. 
Verm. 43 
Convoluta ) lies imbedded in the anterior end of the body, and in Amphi- 
chcurus it fills the whole space between the brain and the front end. 
Delage described it as a nervous organ. It is really a glandular organ, 
consisting of an aggregation of unicellular gland-cells, which are pro- 
vided with long duct-like processes which abut at the anterior extremity 
of the body. The frontal organ of the Accela is represented by homo- 
logous structures in the Rliabdoccela , Alloiocoela, Triclades , Polyclades , 
and even Nemertines. The structure of the genital organs (pp. 46-48) 
is of great importance for Systematic purposes. 
With regard to the Systematic position of the Accela (pp. 49-52), 
author still thinks that they are the most primitive Turbellarians , and 
he does not seek for the ancestors of the latter among the Ctenophora , 
but looks to such a form as Tricfioplax adhccrens of F. E. Schulze. 
Author has distinguished an integumentary muscle-layer in Trichoplax. 
The genera of Accela are classified as follows : — 
I. Familia Proporida. 
Accela with one genital opening. 
1. Genus Proporus (s. str.). No Bursa seminalis. 
2. Genus Monoporus (n. g.). With Bursa seminalis. 
II. Familia Aphanoetomida. 
Accela with two genital openings, the female situated in front of the 
male, with Bursa seminalis. 
3. Genus Aphanostoma. Bursa seminalis unarmed. 
4. Genus Convoluta. Bursa seminalis with one chitinous 
mouthpiece. 
5. Genus Amphichcerus (n. g.). Bursa seminalis with two sym- 
metrically-placed mouthpieces. 
Description of species, pp. 53-74. The genus Cyrtomorpha dis- 
appears, its species being relegated to Convoluta. Nadina awaits further 
investigation. 
IIaberlandt finds that the chlorophyll-cells of Convoluta roscoffensis 
possess a similar organization to that of certain lower Algce. But they 
have no cell-wall, and when isolated are unable to form one. They are 
incapable of leading an independent existence. Phylogenetically they 
are undoubtedly derived from Algce ; but their adaptation to a symbiotic 
mode of life has reached such a stage that they form a definite and 
inseparable portion of the tissues of the worm, namely, they constitute 
its assimilating tissue. The adult worms apparently do not take tip 
nourishment in any other way than through the mediation of the 
chlorophyll-cells. 
Woodworth describes structure of Phagocata , a Triclad which is 
remarkable in possessing, besides the median pharynx which opens into 
the intestine at the junction of its three maiu trunks, many additional 
pharynges, which are joined to the two lateral trunks of the intestine. 
They all lie in a common chamber, which embraces the middle half of 
