264 On certain Species o/'^olosoma. 



known *. It Las 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 setje 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 sufiiciently 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 JEolosonia tenehrarum and jEoIosoma 

 Headleyi, 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 jEolosoma 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 tliat it is equally surprising to 

 find the same or quite different pigments in closely allied 

 forms. 



In my paper upon yEoJosoma tenehrarum I mentioned that 

 the pigment was dissolved by turpentine, forming a bright 

 yellow solution, which after a time became bleached. I have 

 treated jEoIosoma quaternarium with the same substance 

 and found an analogous reaction ; the pigment was dissolved, 

 but slightly altered in colour, becoming reddish brown. I 

 have not had tlie opportunity of applying this test to yEolo- 

 soma Headleyi. The alteration in colour, which is similar to 

 that produced upon other colouring substances by turpentine 

 (see for example Krukenberg, Vergl. physiol. Studien, 

 1. Heihe, 2 Abth. p. 68), may perhaps be due to ozone. 



§ 2. Further Notes upon iEolosoma Headleyi. 



In my paper descriptive of this species (" Observations 

 upon an Annelid of the Genus ^olosoyna,''^ Proc. Zool. Soc. 

 1888, p. 218) I have pointed out its resemblances to and 

 differences irom jEoIosoma variegatiim, 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. jEolosoma macrogader) too im- 

 perfectly described by Schmarda (' Eeise um die Erde/ Bd. ii. p. 10, 

 pi. xvii. fig. 154 ) may prove to be exceptions to this statement. 



