241 SOME OBSERVATIONS ON NEMATOIDEA IMPERFECTA. 



Nyctotherus.* — Proc. Acad. Nat. Sci., vol. 4, p. 233. 



Body ovate, finely vibrillated, dilated posteriorly, compressed anteriorly; investing tunic 

 granular and marked with longitudinal lines; antero-inferiorly and middle line of the body 

 furnished with a semicircle of large vibrillce, anterior to which is a large, granular, areola; 

 posteriorly, with a short fissure passing inwards and downwards. 



1. Nyctotherus velox. — (PI. 11, fig. 49, a. b. c. d.) Proc. Acad. Nat. Sci., vol. 4, p. 233. 



Body white, translucent, ovate ; anteriorly obtusely rounded ; posteriorly angular. Ante- 

 rior areola faintly granular, trapezoidal, with bulging sides. Interiorly furnished with 

 several minute vacuolar, and usually one large and globular situated just at the end of the 

 posterior fissure. 



Length, from 1.254th to 1.180th in.; breadth, from 1.320th to 1.254th in. 



This species is found in the commencement of the large intestine of Julus marginatus, 

 occasionally in thousands. It moves with great ease and grace in the water, and after 

 some time the external tunic bursts and allows large globules of the sarcodic mass to pro- 

 trude, which often separate, as in fig. 49 d., and the animal is gradually destroyed. 



2. Nyctotherus ovalis. — (PI. 11, fig. 50.) Proc. Acad. Nat. Sci., vol. 5, p. 100. 



Translucent, oval; posteriorly, obtuse. Anterior areola large, granular. Posterior fis- 

 sure passing downwards. 



Length, 1.187th in.; breadth, 1.250th in.t 



Found in the intestinum tenue of the Blalta oricntalis, occasionally in large numbers. 



Boco Julidis.— (PI. 11, fig. 51.) Proc. Acad. Nat. Sci., vol. 5, p. 100. 



Body translucent, faintly greenish, faintly granular, with one or two large round 

 vacuolar, and numerous minute ones; form changing, usually globular, oval, or pyriform; 

 caudae twice the length of the body, very active, frequently becoming twisted into a ring 

 at the extremity. 



Diameter of body, 1.3000th of an inch. 



This animalcule is found in the large intestine of Julus marginatus, with Nycotlicrus 

 velox, often in millions. 



references to figures, (plate 11.) 

 Figures all magnified. 



Figs. 42 — 45. — Nematoideum cavitatis abdominis Passuli cornuti. 

 43. — Posterior extremity in outline. 



I I. — Posterior extremity. The large internal transparent masses are observable, and portions of fluid and 

 nuclear bodies expressed from the anus. 

 45. — Anterior extremity. 



40 N. cavitatis thoracis P. cormiti. 



47. — N. intcstinorum Jlrmadillonis pillularis. A portion of membrane is observable attached to the mouth. 

 48. — N. integumenti Lumbriculi limosi, doubled up within its sac. 

 49. — a, b, c, d, Nyctotherus velox. 

 50. — N. ovalis. 

 51. — Bodo Julidis. 



* Ni'xfofljjpaj. 



t The measurements given in the Proc. Acad. Nat. Sci. are erroneous, being a mistake of the printer. 



