118 MR. H. CHARLTON BASTIAN'S MONOGRAPH 



9. PLECTUS \ Bastian. 



Enoplus}, Dujardin. 



Gen, Char. Jiody tapering at eitlier extremity. Caudal sucker pointed. Integument 

 having transverse striae ; setae or papilla} around head occasionally present. Flia- 

 ryngeal cavity slightly dUated at first, then narrow and elongated ; commencement 

 of oBSophagus marked hy 4-6 bright slightly curved Hnes. CEsophagns cylindrical, 

 hut having an oval swelling posteriorly, in which is contained a horny valvular 

 apparatus of the same shape. Intestinal cells mostly containing rather few pale- 

 coloured fat-particles. Vulva about middle of body. Uterus bifid ; segments short, 



symmetrical. Omrian tubes short, broad, reflexed. S])icides 



Excretory gland having linear duct twisted round oesophagus, and opening nearly 

 opposite its middle in length. Lateral vessels with distinct double outline, com- 

 mencing at lateral circular markings of integument, opposite pharyngeal region of 

 body, and terminating posteriorly. 

 Movements active. 



1 have little doubt that the Nematoids found by Spallanzani in tufts of moss, and 

 ascertained by him to possess the remarkable power of resuming all the functions of life 

 after prolonged periods of torpidity and more or less complete desiccation, belonged to 

 this genus; and it seems probable also that Dujardin, in his observations, has con- 

 founded together such forms as the members of this, and those corresponding to the 

 type of his genus Bhabditis. I have found individuals of this genus in specimens of 

 lichen brought by my friend Howard Fox, Esq., from Norway, and which had been 

 lying in his cabinet for four years ; none of the animals, however, exhibited signs of life 

 after prolonged immersion in water. In these specimens of lichen, as well as in the 

 fresh patches of Parmelia parietina whicTi I have examined in this country, I have found 

 the Nematoids associated with tAvo or three species of Rotifera, as well as the peculiarly 

 slow-moving little animals designated "Sloths" by the Abbe Spallanzani-, and belong- 

 ing, I believe, to the genera Emydkim and Macrobiotus — all possessing about the same 

 tenacity of life. 



1. P. PARiETiNUS, n. sp. (Plate X. figs. 79, 80.) 



Female, length -^f, breadth 4^". 



External Characters. — Body white, tapering at either extremity, more especially pos- 

 teriorly. Head truncate, provided with a circle of four large rounded papillae. Integu- 

 mental striae transverse, ^§000 " apart. 



Pharyngeal cavity ^^" long. (Esophagus about ^th of total length. Intestinal cells 

 indistinctly tessellated, containing rather few light-coloured fat-particles. Anus -o^" 

 from posterior extremity. Vulva at middle of body. Excretory ventral gland having 

 twisted duct opening at ^33" from anterior extremity. Lateral vessels commencing at 



' nXe<.-ros, hoisted, in allusion to the particular character of the duct of its ventral gland. 



2 Tracts on the Nat. Hist, of Auini. and Veget., translated by Graham Dalyell, ed. '1, vol. 11. pp. 129-lGG. 



