NOTK ON A NEW BlilTISn EOIMUROID GEPfiyREAN. 375 



vesicle and spot are distiuctly visible (tig. 33), and a peri- 

 pheral clearer zone of considerable width. The ripe ova from 

 the uterus (fig. 32) are more opaque, and are almost filled 

 with yellow granules, the germinal vesicle being no longer 

 visible, and the clear peripheral zone very narrow (fig. 34). 

 I was able by slight pressure to squeeze a line of ova out from 

 the uterus through the nephridiopore, as shown in fig. 26. 



Nothing specially noteworthy was noticed in connection 

 with the blood-vessels, the nerve system, and other organs. 



No coloured corpuscles were found in the coelomic fluid, 

 and no rudimentary males were seen. These and other mor- 

 phological points are more fully discussed below in determin- 

 ing the systematic position (see p. 378). 



The Green Pigment. 



One of the most remarkable and interesting points about 

 this worm is certainly its beautiful green pigmentation. When 

 alive the colour was a well-marked apple-green, and the speci- 

 mens preserved in forraol have retained a good deal of the 

 colour, although the fluid has also become coloured green. The 

 specimen put in spirit has lost its colour altogether, and the 

 spirit has not acquired any green tint ; while in the forraol, on 

 the other hand, the fluid has become coloured, and the specimens 

 have retained their green appearance. I have used the green 

 formol solution for an examination of the spectroscopic charac- 

 ters of the pigment, and my friends Professor Sherrington and 

 Dr. Noel Paton have kindly investigated samples for me, and 

 have given me their results. I am indebted to these physio- 

 logists and their assistants for the information that follows. 

 Professor Sherrington states : 



" The dilute formol in which the Thalassenia has been lying was clear, but 

 tinted a pale greenish blue, — in fact, a " sea " colour. Examined in a layer 

 20 centimetres deep before a Hilger single flint-prism spectroscope illuminated 

 by a Welsbach incandescent gas lamp, the following localisation of absorj)tioa 

 was obtained (see PI. 28, fig. 35). From the violet end up to nearly as far as 

 the solar line F, from the red end up to the solar a, between the solar lines 

 C and D a single very definite broad band of shadow. ^^ diluting the fluid 

 or diminishing the thickness of the layer examined until the band between 



