FREE-LIVING FRESH-WATER NEMATODES 53 



three or four occupying a distance equal to half the length of the tail. 

 The two equal, straight spicula are rather obscure. Their length is no 

 greater than the length of the anal body diameter. Oblique copulatory 

 muscles are seen in the vicinity of the spicula, and there is a refrac- 

 tive element passing backward from the accessory piece toward the 

 ventral side of the tail near the anus, which may be muscular, or 

 possibly chitinous and serving for the attachment of muscles. The 

 ejaculatory duct is about one-third as wide as the body, the vas def- 

 erens somewhat wider. Whether there are two testes or only one has 

 not been determined. There is a broad, rounded, blunt end of a 

 testis located as far behind the base of the neck as this latter is behind 

 the anterior extremity. 



Habitat: Big Lake, Fla. Bouin solution to glycerine. 



PLECTUS, Bastian, 1865. 

 Fig. 10, Plate IV. 



35 



2. 10.7 IQ. '49' 92.6 



10. Plectus tubifer, n.sp. .74 mm. 



2.1 34 3-5 3-2 2.3 



The skin is of medium thickness, colorless, and traversed transversely 

 by fine, plain striae. The striae are of such a size that about twenty of them 

 occupy a space equivalent to the body diameter. There are no hairs on* the 

 surface of the body, but throughout the length of the body, more particularly 

 on the submedian lines, may be seen very faint markings in the cuticle, which 

 indicate the location of four rows of pores connecting with interior organs. 

 Immediately behind the lateral organs one sees the first of the series of pores 

 located in the lateral line. This first pore, though much smaller than the 

 lateral organs, is yet somewhat larger than the succeeding ones, which grad- 

 ually spread out to form two submedian rows. The total number of these 

 pores on one side (of the male) is about one hundred; that is, there are about 

 two hundred in all. The six low, rounded lips are rather massive, and are 

 arched together over the pharynx. These lips appear to be armed with 

 chitinous processes on the inner surface, these processes surrounding a short 

 napiform vestibule leading to the pharynx proper. If any labial papillae are 

 present they are exceedingly minute ; what appear to be traces of papillae 

 may occasionally be seen. The lateral organs are well forward, being lo- 

 cated only slightly behind the cephalic setae. They present transversely 

 elongated contour markings open on the posterior margin. The lateral fields 

 appear to attain a considerable width and two chitinous, lateral markings 

 close together with a third between them, appear to indicate the existence of 

 a wing on each side of the body. 



