118 MR. H. CHARLTON BASTIAN’S MONOGRAPH 
9. PLECTUS !, Bastian. 
Enoplus ?, Dujardin. i 
Gen. Cmar. Body tapering at either extremity. Caudal sucker pointed. Integument 
having transverse striæ; setæ or papillæ around head occasionally present. Pha- 
ryngeal cavity slightly dilated at first, then narrow and elongated; commencement 
of cesophagus marked by 4-6 bright slightly curved lines. (Esophagus cylindrical, 
but having an oyal swelling posteriorly, in which is contained a horny valvular 
apparatus of the same shape. Intestinal cells mostly containing rather few pale. 
coloured fat-particles. Yulva about middle of body. Uterus bifid ; segments short, 
symmetrical. Ovarian tubes short, broad, reflexed. Spicules . . . . . . ., 
Excretory gland having linear duct twisted round cesophagus, and opening nearly 
opposite its middle in length. Lateral vessels with distinct double outline, com- 
meneing at lateral cireular markings of integument, opposite pharyngeal region of 
body, and terminating posteriorly. | 
Movements active. 
I 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 Rhabditis. 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 which I have examined in this country, I have found 
the Nematoids associated with two or three species of Rotifera, as well as the peculiarly 
slow-moving little animals designated * Sloths ” by the Abbé Spallanzani?, and belong- 
ing, I believe, to the genera Emydium and Macrobiotus—all possessing about the same 
tenacity of life. 
1. P. PARIETINUS, n.sp. (Plate X. figs. 79, 80.) 
Female, length 4", breadth 41". 
External Characters.—Body white, tapering at either extremity, more especially pos- 
teriorly. Head truncate, provided with a circle of four large rounded papilla. Integu- 
mental striæ transverse, 15155" apart. 
i Pharyngeal cavity sis" long. Œsophagus about ith of total length. Intestinal cells 
indistinctly tessellated, containing rather few light-coloured fat-particles. Anus 3h 
from posterior extremity. Vulva at middle of body. Æxcretory ventral gland having 
twisted duet opening at i33 from anterior extremity. Lateral vessels commencing at 
* IMexrös, twisted, in allusion to the 
particular character of the duct of it 3 
? Tracts on the Nat. € duct of its ventral gland 
Hist. of Anim. and Veget., translated by Graham Dalyell, ed. 2, vol. ii. pp. 129-166. 
