104 MARINE FAUNA OF ST. ANDREWS. 



already been noticed * ; so that in the mean time the remarks 

 shall be confined to the PolynoidaJ, three common species 

 of which afford ready means of experiment. In Harmothoe 

 imbricata irritation causes a series of bluish-green flashes 

 at the points of attachment of the scales, and then a steady 

 light for some time. Very pale specimens seem more irri- 

 table than ordinary forms. No pulsations of light are ob- 

 served on the phosphorescent surface of the detached scales. 

 On the whole the light in this species is characterized by its 

 steadiness. It does not readily emit its phosphorescence when a 

 little sulphuric ether is added to the water ; nor does mechanical 

 irritation in these circumstances cause any change in its mani- 

 festation. Acetic acid acts as a poison, causing a momentary 

 gleam as the scales are thrown off, which wholly disappears 

 with the death of the animal and the ejection of the proboscis. 

 If strong methylated spirit be gradually added to the sea- 

 water (In a small Yessel), there is seldom phosphorescence if 

 no mechanical irritation occurs ; the animal perishes with all 

 the scales on its back. The luminous emissions are similar 

 when spirit Is applied to the annelid in the air. Pohjnoe 

 fioccosa seems to be more irritable, and to emit its phosphor- 

 escence more readily than the foregoing at the same points. 

 When one of the scales Is detached, the greenish light is 

 o-Iven off as if In pulsations from the surface of attachment, 

 somewhat quickly at first, then slower, and finally dis- 

 ajipearlng. In Evarne inqmr, again, the detached scales give 

 off a flashing light, such as might be caused by a swift 

 series of waves, and which quite differs in character from 

 tliat In P. foccosa. 



The Gephyreans are not so abundant as on the muddy flats 

 of the west and south, where swarms of the common forms 

 are found in a single spadeful. The highly characteristic 

 Echiurus vulgaris^ however, occurs, often in great numbers ; 

 and though Priajmlus caudatus is not met with In the lit- 

 toral region, nor so large as in the Hebrides, still it is 

 not rare In deep water, and is frequent in the stomachs of 

 fishes. 



* Ann. & Mas. Nat. Hist. 4th ser. 1872, vol. ix. pp. C & 7. 



