1889.] MR. F. E. BEDDARD ON ZOLOSOMA TENEBRARUM. 55 
pl. 9. fig. 9), in many of which the pigment is collected into a 
globule lying in the middle of the cell; this globule is, according to 
Moseley (“‘ On Stylochus pelagicus, &c.,” Quart. Journ. Mier. Sci. 
vol. xvii. 1877, p. 30), of a fatty nature, which is a further point of 
similarity to olosoma. 
A resemblance—perhaps of greater importance—is shown to 
Ctenodrilus; this genus consists of three species, in all of which 
the integument is dotted over with coloured spots. In Ctenodrilus 
monostylos (v. Zeppelin, ‘‘ Ueber den Bau und die Theilungs- 
vorgiinge des Ctenodrilus monostylos,”’ Zeitschr. wiss. Zool. Bd. xxxix. 
p- 617) and in C¢. pardalis (v. Kennel, ‘‘ Ueber Ctenodrilus pardalis,” 
Arbeit. Zool. Inst. Wiirzburg, Bd. v. 1882, p. 375) these spots 
are dark green. In the third species, Ct. parvulus, Dr. Scharff 
(On Ctenodrilus parvulus,” Quart. Journ. Micr. Sci. vol. xxvii. 
1887, p. 592) states that the spots are dark green or violet, and 
that the colouring-matter is carried by an oily substance. I am not 
quite clear from Dr. Scharff’s paper whether he means to say that 
the colour of these spots in Céenodrilus parvulus is violet, or whether 
green and violet spots both occur. In any case, the alternation of 
green and violet is most suggestive in the light of what has been 
already said regarding the change of the green pigment of Holosoma 
tenebrarum into violet by an alkali: moreover, Prof. Hartog informs 
me that he observed ‘ claret-coloured ” spots as well as green in one 
individual of 42. variegatum; this fact is evidently of importance. 
Moseley’s observations upon the blue and red colouring-substances 
of two land-planarians found at Sydney, N.S.W. (“ On the Colour- 
ing-matters,” &c., loc. cit. p. 11), suggest, however, the need for 
caution in drawing such an inference; he found that the due 
pigment of one of the worms was converted into red by the action of 
acids, and surmised therefore that the red pigment of the other 
species would prove to be identical with this pigment; but this 
surmise proved to be incorrect. 
I have already suggested that the green pigment of Molosoma 
tenebrarum may be a respiratory pigment, capable of oxygenation and 
deoxygenation ; the peculiar reaction with iodine which has been 
referred to may possibly fit in with this hypothesis. I may also 
mention that the change in colour of the cells from a bright yellow- 
green to a dull olive-brown is very suggestive of a corresponding 
taking up and giving off of oxygen, but I have no positive facts to 
offer, and the proof is indeed extremely difficult. 
The blood of Holosoma tenebrarum is quite colourless at all times. 
The plasma of the blood of Holosoma quaternarium and Ai. ehrenbergi 
is stated by Vejdovsky (doc. ci¢. p. 18) to be colourless ; but he de- 
scribes cells with branched processes attached to the walls of the 
dorsal vessel in these species and in AZ. tenebrarum, which contain a 
yellow pigment. This may be hemoglobin, but there are no obser- 
far as I can remember). I made a few notes upon the worm, which I have un- 
fortunately lost; I hope, however, to have an opportunity of finding the 
Planarian again. It was not Vorter nor Mesostomum nor Convoluta. 
