AMPHITHOfi LITTORINA. 423 



brown, and are nearly of the same length, and are not 

 quite half the length of the animal;* the inferior have 

 the joints of the peduncle armed with strong hairs. The 

 first two pairs of legs are subequal, but the second is 

 rather the larger. There is a deep semilunar fissure 

 between the wrist and the hand and between the wrist 

 and the preceding joint, which does not occur in A. rubri- 

 cata. The first pair have the hand gradually tapering 

 to the extremity; the palm is straight and occupies 

 nearly the whole length of the inferior margin. The 

 second pair have the hand continuous with the wrist, and 

 formed much like that of the first pair ; the palm is long 

 and not clearly defined ;f the finger is nearly as long 

 as the inferior margin, and has the inner margin smooth. 

 The first two pairs of walking legs are short and robust. 

 The three posterior gradually increase in length and 

 have the inner margins of the hands furnished with a 

 longitudinal row of short stout spines. The posterior pair 

 of caudal appendages do not reach beyond the preceding 

 pair, and have the inner ramus foliaceous and the outer 

 styliform, and furnished with two short, hook-like spines. 

 The central tail-plate is obtusely triangular. The colour 

 of the animal is olive-green, covered all over, especially 

 on the sides, with minute black spots changing when 

 dead to a sand colour and marked on the back with 

 numerous impressed punctures. 



This species is generally found amongst the weed close 

 in shore, associated with Gammarus locusta. It may 

 readily be detected by its size : like " a Triton amongst 



* Dr. Johnston describes the upper antennae in his 0. punctatus as nearly 

 as long as the body. 



t Dr. Johnston describes the hands of the second pair as having an obsolete 

 tooth. 



