450 APPENDIX II 



nent part in all these shrimps is here arranged in obliquely trans- 

 verse lines or bars on the body, and in specks, blotches, or rings 

 on the legs. 



In the numerous species of Spirontocaris, the body is shaped 

 as in the preceding, but the beak is much shorter and variously 

 shaped and toothed, but always thin and compressed. The first 

 pair of legs have small but well-defined claws ; those of the second 

 pair are notable in being very slender and in having the wrist or 

 antepenultimate segment divided into many small pieces jointed 

 together and tipped with a minute claw. 



Besides the true shrimps there swarm at the surface numbers 

 of transparent schizopods, or cleft-footed shrimps, known as 

 Mysis, which swim in immense shoals, and form the main food of 

 the sea-trout. These shrimps are of small size, an inch or less 

 in length, with large, dark eyes, and have seven instead of five 

 pairs of trunk-legs, devoid of claws, but each provided with an 

 appendage adapted for swimming. The eggs are carried by the 

 female in a marsupial pouch beneath, which has suggested the 

 name of " opossum-shrimp." 



The Cumacea are still smaller crustaceans, half an inch or less 

 in length, distinguished by having the anterior half very robust, 

 the posterior half slender, the eyes sessile, not stalked as in the 

 crabs and shrimps, the carapace leaving five segments of the trunk 

 exposed, the antepenultimate segment of the body the longest, 

 the tail fan composed of three branches. They are abundant in 

 sand at the depth of a few fathoms. 



The Phyllocarida, or leaf-shrimps, so called on account of the 

 laminar or leaflike expansions with which their legs are provided, 

 are represented by Nebalia bipes, which was dredged by Dr. Pack- 

 ard at the mouth of Henley Harbour in four to twenty fathoms. 

 This little creature, less than an inch in length, is most remarkable 

 for the great size of its ancestors, whose paleozoic remains measure 

 nearly two feet. 



The Amphipods, or sand-fleas, are by far the most abundant 

 of the Crustacea, both in species and individuals. They are found 

 on the sand near high-water mark, in seaweed, and among rocks 

 in shallow water, and may be dredged at any depth. None is of 

 large size ; individuals range from about one-eighth of an inch to 

 an inch. Many of them hop like fleas. Others move rapidly 

 while lying flat. They act as scavengers, often nearly consuming 

 a dead fish before it can be hauled in. They are sessile-eyed, 

 laterally compressed, somewhat crescent-shaped, with rounded 

 backs, and usually of stout build. An exception is the slim skele- 

 ton-shrimp, Caprella, which clings to finely branched seaweed 

 and is so flexible that it can bend itself into a ring. Another 



