INTRODUCTION. 



The tidal rocks, again, which are mostly covered by sea- 

 weeds, present a varied and prolific site for many species. 

 The rock-pools are both frequent and picturesque ; and they 

 possess many undisturbed stones, often of large size, the under 

 surfaces of which are most favourable for the growth and 

 shelter of numerous forms — though of course they cannot be 

 compared in this respect with the littoral stones at Herm, which 

 have a profusion of rare crabs, annelids, ormers and other 

 mollusks, polyzoa, hydroids, and the yellow, red, purple, green, 

 and white sponges. The rocks may conveniently be divided 

 into the East and West Kocks, the former stretching from the 

 pier to the east, the latter from the pier westwards. The rock- 

 pools in these resemble miniature oceans of surpassing beauty. 

 The borders of the clear basins are luxuriantly fringed with 

 different kinds of seaweeds — Fucus serratus,Halidrys siliquosa, 

 Furcellaria, and Chondrus, and the broad blades of Laminaria 

 sacckarina hang sombrely downwards and trail on the bottom. 

 These sober tints are here and there relieved by the fine green 

 tufts of Cladophora and the broad Ulva, the dark red of Cera- 

 mium rubrum, and the pinkish hues of Corallina. The latter, 

 in some of the clearest and finest pools, is not infested by the 

 little white coils of Spirorbis, so that it is variegated only by 

 its own whitish tips, which are in strong contrast in the quiet 

 depths with the dull olive roots of the tangles. 



The pools are tenanted by representatives of all the animal 

 subkingdoms ; and many species are in profusion. Cotti, gun- 

 nels, blennies, shannies, gobies, and sucking-fishes swim in 

 the clear water or glide under the protecting seaweeds. 

 Bunches of Furcellaria and Fuci afford a site for Eolidm ; and 

 Hyas, Carcinus, and Pagurus nestle in their shade or peram- 

 bulate the bottom. In some pools beyond the Maiden rock 

 Pakemon squilla abounds, darting hither and thither with 

 great velocity or poising its long antennae over the seaweeds 

 in graceful curves. Minute crustaceans and mollusks people 

 the laminarian blades, while the roots give shelter to many of 

 the forms previously mentioned. The larger mollusks (Buc- 

 cinum, Purpura, and Trochus) crawl on the same leaves, or 

 adhere in the society of limpets to the margins of stones. 

 The under surface of the latter reveals a varied fauna. It is 



