392 



TRICOMA AND OTHER NEW NEMATODE GENERA, 



one-tenth as wide as the body. The oesophagus is anteriorly one- 

 fourth to one-third as wide as the neck ; posteriorly it is three- 

 fourths as wide as the neck. This change in relative diameter 

 takes place gradually behind the nerve-ring. The latter is three 

 times as wide as the oesophagus at the point 

 encircled and is in all cases oblique. The excre- 

 tory pore is situated just behind the nerve-ring. 

 There is a distinct cardiac 

 collum. The anterior half 

 of the tail is conoid from in 

 front of the inconspicuous 

 anus. The posterior half 

 of the tail is nearly cylin- 

 drical, having a diameter 

 one-fourth as great as the 

 body-diameter at the anus, 

 but expands at the naked 

 terminus into a bulb 

 nearly twice as wide. 

 The reflexed portions of 

 the ovaries reach about 

 half-way to the vulva and contain several 

 developing ova. One or two thin-shelled unseg- 

 mented eggs nearly twice as long as the body is 

 wide and about half as wide as long are commonly to be seen in 

 each uterus. Male unknown. 



Hah. — The females of this species were common amoug alg£e on 

 the coast of Ceylon in the month of March, 1889. 



Fig. 4. — I, female of 

 Pelagoneina simplex. II, 

 lateral view of head of same 

 worm more hitrhlj' magnified. 



III, tail of the same worm. 



IV, ventral view of head of 

 same worm. 



a, mouth. 



b, pharynx. 



c, nerve-ring. 



d, excretory pore. 



e, cardiac constriction. 

 /, anus. 



g, vulva. 



h, egg- 



i, fold in ovary. 



j, nucleus. 



k, rudimentary tooth at base 



of pharynx. 

 I, anus. 



III. Demonema, new genus. 



The genus Deinonema belongs to the Enoplus family. Three 

 apophyses extend backward from the mouth, but the distinct teeth 

 characteristic of Unoplus are absent. Nevertheless, the mouth 

 opens after the manner of a three-jawed chuck as in Eyioplus and 

 the three lips are here armed with numerous powerful teeth. 

 Spiral lateral organs occur near the mouth. The female sexual 



