264 On certain Species of Aolosoma. 
known *. It has a more complex brain as well as consider- 
able traces of a ventral nerve-cord; the number of segments 
is larger and the nephridia are more numerous, and finally 
the specialization of the sete points in the same direction. 
Treated with ammonia or with potash the brown colouring 
was at once dissolved and converted into a fine purple; the 
purple colour rapidly disappeared,‘and I never succeeded in 
treating it with a mineral acid sufficiently promptly to see if 
the brown colour could be restored. This reaction appears to 
indicate that the brown colouring-matter is nearly related to 
the green colour of Molosoma tenebrarum and Afolosoma 
Headley? as all three pigments were changed to purple by 
the action of an alkali; in the last two species, however, the 
purple was not of so vivid a hue as in Aolosoma quater- 
narium, owing apparently to the presence of a granular 
detritus precipitated by the action of the reagent ; this precipi- 
tation was not formed when Molosoma quaternarium was 
treated with this reagent. 
It is, however, important to notice that the three colouring- 
matters have something in common, though researches into 
animal pigments have shown that it is equally surprising to 
find the same or quite different pigments in closely allied 
forms. 
In my paper upon Aolosoma tenebrarum I mentioned that 
the pigment was dissolved by turpentine, forming a bright 
yellow solution, which after a time became bleached. I have 
treated Molosoma quaternarium with the same substance 
and found an analogous reaction ; the pigment was dissolved, 
but slightly altered in colour, becoming reddish brown. 1 
have not had the opportunity of applying this test to Molo- 
soma Headleyt. The alteration in colour, which is similar to 
that produced upon other colouring substances by turpentine 
(see for example Krukenberg, Vergl. physiol. Studien, 
I. Reihe, 2 Abth. p. 68), may perhaps be due to ozone. 
§ 2. Further Notes upon Molosoma Headleyi. 
In my paper descriptive of this species (“ Observations 
upon an Annelid of the Genus Molosoma,” Proc. Zool. Soc. 
1888, p. 213) I have pointed out its resemblances to and 
differences from olosoma variegatum, with which species it 
might possibly be confounded ; a short time after completing 
my study of the species, so far as the material at my disposal 
* Some of the remarkable forms (e. g. olosoma macrogaster) too im- 
perfectly described by Schmarda (‘Reise um die Erde,’ Bd. ii. p. 10, 
pl. xvii. fig. 154) may prove to be exceptions to this statement. 
