126 MR. H. CHARLTON BASTIAN’S MONOGRAPH 
such as glycerine, almost immediately shrivel up, owing to the rapid osmosis of fluids 
from within; or, when placed in a colouring solution of magenta, the whole of their 
tissues become speedily and uniformly dyed of the same hue. But if a species of either 
of these four land and freshwater genera be submitted to the same conditions, they 
exhibit totally different results: they will continue to move about in glycerine for about 
fifteen or twenty minutes before commencing to shrivel, and’ will remain nearly as long 
in a strong magenta solution with the body uncoloured, save for a very short distance 
from the mouth and anus. Both these experiments seem to indicate that there is not 
such a free communication through the integument, in these species, between the in- 
ternal parts of the body and the external medium, and that the integument is hermeti- 
cally sealed, excepting at such natural apertures as mouth, anus, and vulva. This 
property may be one of the factors concerned in producing the extraordinary tenacity of 
life observed in these animals,—one of small significance, however, when we attempt 
. to explain the very prolonged periods of suspended animation, extending over a series of 
years. This power of remaining for lengthened periods to all intents and purpose 
dead, inasmuch as there is a negation of all that we are apt to consider as the charac- 
teristic attributes of life, save that, like seeds, they still retain the potentiality of re. 
suming their vital manifestations under the influence of suitable external conditions, 
must, doubtless, depend upon inherent peculiarities of the tissues themselves, beyond 
the reach of detection by optical instruments even of the highest power. | E 
Another peculiarity of these four genera is the fact that they all possess the excretory 
gland in a modified condition, though I have not met with it at all in any of the other 
land and and freshwater types. | 
1. T. DAvarwir n. sp. (Plate X. figs. 109-111.) 
Female, length 437^", breadth 775”. | 
External Characters.—Body tapering at both extremities, especially towards posterior. 
Head narrowed, truncate. Integument thick; striæ transverse, distinct, TE, apart. 
Spear large, +235” long. (Esophagus th of total length ; posterior part, behind median 
swelling, gradually widening. Intestine not very distinct from body generally, being 
obscured by large, coarse, colourless granules. Anus so from posterior extremity. 
Vulva considerably behind middle of body, Js from anterior extremity. Eacretory 
duct distinct, opening opposite posterior part of cesophagus, and extending backwards 
for about 319 , where it terminates in an ovoid sac. | 
Male, same size as female. 
Œsophagus shorter. Anus 145° from posterior extremity. Spicules rather narrow, 
717 long; accessory piece of about half this length. Ale transparent, narrow; ex. 
tending, on either side, from slightly above to a little below the anus. ! 
Hab. From sheet of moss covering large boulder lying in a freshwater stream, Fal- 
mouth. 
2. T. rrıcret. (Plate X. figs. 112-114.) 
Needham, Micr. 99, tab. v. 7. 
Baker, Micr. Expl. 80, tab. v. fig. 9. 1, 2. 
Roffredi, in Journal de Phys. 1775, p.369. . 
