212 NATURAL HISTORY. 



the shell of the living Balanus balanoides. A second species, also referred to the genus Cryptothyria 

 (Fig. 33, c), is found resident within the body of another Cirripede (Peltogaster), which itself is 

 parasitic on the tail of a Crab (Portunus or Carcinus). Those belonging to the genus ^Ega have all 

 the feet furnished with a robust curved finger, sharp at the tip for seizing and holding on to fishes, 

 as the Codfish, Whiting, &c., to the exterior of which they adhere. The Eurydice pulchra, common 

 in the River Dee in Cheshire, will actually fasten upon bathers if they remain quiet in the water, 

 adhering to the skin even after they emerge from the river. 



OEDER IV. AMPHIPODA. 



In the AMPHIPODA the head is small, representing only the first seven cephalic rings, the seven 

 thoracic and the seven abdominal being nearly equally well developed. The eyes are sessile or fixed, 

 the body-rings are compressed laterally, as in the Lobster, and they possess both swimming and 

 walking legs indeed, we might add, leaping ones also, for many of them pass much of their time 

 in this mode of progression on the shore. The first and second pairs of appendages become modified, 

 in the male, into strong claspers, by the greater development of the hand and the movable character 

 of the terminal joint, whilst the last pair of limbs are converted into leaping legs, like those of the 

 Grasshopper. The gills are attached to the thoracic feet, as is also the incubatory pouch of the 

 female. The heart lies beneath the dorsal surface of the body. To this division belongs the 

 well-known " Sand-hopper " (the Talitrus locitsta of Linnaeus), one of the most abundant forms 



everywhere around Britain, living between 

 high and low water-mark, where it feeds on 

 decaying garbage, both animal and vegetable, 

 existing in myriads on some of the sandy 

 shores. They never enter the water, but 

 yet seem to require a certain amount of 

 moisture to enable their branchiae to perform 

 their function. They burrow under moist 

 seaweed and in damp sand. The young 

 Fig. 34. AMPHIPOD (Orchestia darwinii). MALE. Talitrus usually remains with the parent for 



some time after they attain to maturity. 



Another genus (Orchestia) also lives out of the sea, choosing moist places, but not burrowing as 

 Talitrus does. On the British coast Orchestia lives within reach of the sea-spray, but some species 

 in the Southern Hemisphere live many miles inland, choosing terrestrial plants for their abode. 

 They are sometimes found at 1,500 feet above the sea-level (Fig. 34). 



Sulcator lives along the sea-margin, making tracks upon the sandy shore, which, when in after 

 years they have become hardened into sandstone, form puzzles for the palaeontologist, who finds it 

 sometimes difficult to decide whether they are worm-tracks or impressions of plants. 



Blind species of Niphargus and Crangonyx are found inhabiting subterranean fresh waters in 

 wells in the Chalk and Oolitic rocks of various parts of England and Europe. One species of 

 Niphargus inhabits the hot springs of Italy. 



The CMura terebrans is one of the most injurious xylophagous Crustaceans known. It is 

 commonly found associated with another wood-borer, the Limnoria lignorum (the Gribble), an 

 Isopod, which, though smaller, is even more prolific than Chelura. The excavations made by Chelura 

 are larger and more rapidly executed than those of Limnoria. 



In all these forms an extreme degree of maternal solicitude seems to be developed, which exhibits 

 itself not only in carrying the young, after hatching and brooding over them like a hen over her 

 chickens, but in Podocerus the parent builds a nest in which the young are nurtured and protected, 

 more after the manner of young birds than of such comparatively lowly-organised forms as Crustacea. 

 The KEMODIPODA form (according to Spence Bate and J. 0. Westwood) an aberrant group of 

 AMPHIPODS. The coxal joint of all the legs is fused with the body, and the tail is reduced to 

 a rudimentary condition. 



The popular name of Spectre, or Skeleton Shrimp, seems very appropriate to Caprella (Fig. 35). 

 It lives amidst seaweeds and zoophytes, and is very active, scrambling from branch to branch. 



