148 Dr. W. C. M'Intosh on the 



shall l>e confined to the Polynoidge, 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 vessel), 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. Polynoe 

 floccosa 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 given 

 off as if in pulsations from the surface of attachment, some- 

 what quickly at first, then slower, and finally disappearing. 

 In Evarne impar, 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 that in P. floccosa. 



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 Priapidus caudatus is not met with in the littoral 

 region, nor so large as in the Hebrides, still it is not rare in 

 deep water, and is frequent in the stomachs of fishes. 



The Nemerteans, again, are especially abundant between 

 tide-marks, though some range thence to deep water, and a 

 few occur only in the latter. AmpMporus lactifloreus is 

 common under stones, and Linens gesserens is and Cephaloihrix 

 linearis in still greater numbers, especially in muddy places. 

 The great Lineus marinus is frequently found under stones, and 

 occasionally in the pools. Near low water the Tetrastemmce 

 (such as T. rnelanocephala, T. Candida, T. vermicida, T.flavida, 

 and occasionally T. dorsalis) occur in varying numbers, the 

 latter however,' attaining its maximum amongst the red sea- 

 weeds in the laminarian region. By splitting the rocks at 

 fissures Nemertes Xeesii, Lineus bilineatus, Micrura fasciolata, 



