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PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 50. 



tail, enlarges a little just anterior of the most posterior papillae, and 

 then forms a small round ligulate tip extending 14 ix. beyond the 

 posterior extremity of the body proper. There are eight pairs of 

 fungiform caudal papillae, asymmetrically placed. The four pairs 

 of preanal papillae are the larger, being 20 /* long, while of the four 

 pairs of postanal papillae those nearer the cloacal aperture are the 

 largest, and they decrease in size posteriorly, those near the tail 

 being 10 /* long. The spicules are very dissimilar. The short one is 



93 fi long and the long one 528 /x long, or 

 almost six times as long as the short one. 

 In profile the short one is sword-shaped 

 with a rounded point. It attains its maxi- 

 mum thickness of 9 /^ at the proximal ex- 

 tremity. From here it curves in an even 

 taper toward the tip. It is striated trans- 

 versely and appears to be hollow through- 

 out. Viewed dorso-ventrally, it appears to 

 be thickest in the middle. The long spicule 

 is of uniform thiclvness throughout except 

 for a slight dilatation at the proximal end. 

 The dilated tip is surrounded by a mem- 

 branous bulb. The long spicule is com- 

 monly found protruded to half its length, 

 the protruded distal portion being bent at 

 right angles to the proximal portion. Each 

 spicule is surrounded by a sheath, the sur- 

 face of which is apparently chitinous and 

 marked with fine maculae, apparently due 

 to depressions. A third piece of sheathing, 

 larger and thicker walled, lies between the 

 spicules near the distal end of the small 

 spicule, and apparently supports the entire 

 structure and holds the two spicules at a 

 fixed distance. Ilroad muscular bands originate near the anus and 

 extend dorso-ventrally and anteriorly or postei'iorly on each side of 

 the rectum and ductus cjaculatorius. The single testis extends 

 straight almost to the proximal end of the esophagus, where it turns 

 and extends parallel to its former course for a short distance, some- 

 times turning anteriorly again. It terminates in a retortaeform ex- 

 pansion. Posteriorly the testis joins the narrow vns deferens, about 

 70 fi long, and this joins a dilated vesicula seminalis, a little more 

 than 1 mm. long and often full of spermatozoa. This is continued 

 posteriorly as the short ductus ejaculatoris. The spermatozoa are 

 small regular globular cells. 



Fig. 2o2.— Gongtlonema neo- 

 PLA.sTicuM. Posterior ex- 

 tremity OF MALE, VENTRAL 

 VIEW. Enlarged. After 



FlBIGER AND DiTLEV.SEN, 19M. 



