102 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



8. is " Pluteus," the larva of an Ophiuroid. x 30. 

 1). is an adult Copepod, Temora longicornis. x 10. 



10. is Sarsia tubvlosa, one of the Medusoids derived 

 from a Zoophyte, x 2. 



11. is Pleurobrachia pUeus, an adult Ctenophore 

 related to Medusae. Nat. size. 



12. is Pseudocalanus elongatus, an adult Copepod. 



x 10. 



13. is a pelagic fish-egg containing the young fish. 



x 10. 



Coming now to rather higher and larger Crustacea, 

 figure XIII. illustrates the Amphipods or Sand-hoppers, 

 and figure XIY. the Isopods or Sea-slaters. These two 

 groups are closely related. In the Amphipods the body 

 is compressed from side to side, the back is generally 

 curved, the legs are long, and face some forwards and 

 the others backwards (see fig. XIII., 1), while a favourite 

 mode of locomotion is by a series of leaps. The leap is 

 effected by means of the hindmost or tail legs, which are 

 bent forward under the body, and then suddenly 

 straightened out so as to toss the body up in the air. 

 The Amphipod shown at 1 [Orchestia littorea) performs 

 this action. Some kinds of these Amphipods are 

 extremely common on our sandy shores, especially under 

 stones or pieces of decaying seaweed. Others, like the 

 Corophium grossipes shown at 2, burrow in the sea- 

 bottom, where some construct tubes and nests of mud or 

 sea-weeds. The curious skeleton-like Caprella linearis (3) 

 creeps up sea-weeds and Zoophytes, and is sometimes seen 

 in eccentric and acrobatic attitudes, such as holding on 

 to a branch by one claw or balancing on one hind leg. 



The commonest sand-hopper on Port Erin beach is 

 Orchestia gammarellus, and this sometimes, when a high 

 tide is accompanied by a shower of rain, swarms out of 



