THE SEA BOTTOM 61 



of tangled Laminaria (Plate 22), a large population lives 

 attached to the weed, among the most common of which are 

 sea mats especially Membranipora membranacea (Plate 22) 

 which forms a delicate latticed encrustation with typical 

 rounded outlines where the colony is actively growing 

 over the surface of the frond. Many hydroids are found, 

 their branching stolons ramifying over the surface, the 

 branches bearing the feeding polyps projecting freely into 

 the water. A little limpet (Nacella pellucida) , distinguished 

 by the blue stripes on its shell, is invariably found browsing 

 on the bulbous hold-fasts of the Laminaria. A great 

 assemblage of animals find a home in this region, many of 

 them so small as not to be discovered without great care ; 



Fig. 3. — Ghost-shrimp or Caprella ( x 5). 



there are small sea slugs which feed on the hydroids and 

 sponges, and many little mussels, worms, snails and starfish, 

 some of which spend their entire lives here and others 

 only their early phases. In the hold-fasts of the weed are 

 worms and one of the boring bivalves, Saxicava. Perhaps 

 the most interesting of the many crustaceans are the 

 grotesquely elongated Caprellids, or ghost-shrimps (Fig 8), 

 which are especially adapted for climbing about on weeds 

 and hydroids, being provided with grasping claws at either 

 end of the body by means of which they progress rather 

 like a " looping " catterpillar. 



Zostera or eelgrass is only found in sheltered pools and 

 estuaries usually rooted in mud, for it is a true grass, not a 



