=Fam. 7. Hippolytidae.=—The first and second thoracic limbs bear chelae, the carpus of the second being divided into two or more segments. The first pair of chelae are not distinctly stronger than the second. _Virbius_ has many species in the littoral zone of all seas, and one species, _V. acuminatus_, is pelagic. _Hippolyte_ also has numerous littoral forms distributed all over the world, but chiefly in the arctic or subarctic seas. _H. varians_, common on the English coasts, shows interesting colour-reactions to its surroundings.[138] [Illustration: FIG. 110.—_Glyphocrangon spinulosa_, from the right side, × 1. (From an original drawing prepared for Professor Weldon.) ] =Fam. 8. Palaemonidae.=—The first two pairs of legs are chelate, the carpus of the second not being subdivided. _Palaemon serratus_, a very common prawn in the British littoral. _Palaemonetes_ in the brackish and fresh waters of Europe and N. America. =Fam. 9. Glyphocrangonidae.=—The first pair of legs are subchelate, the carpus of the second pair is subdivided, and the rostrum is long. _Glyphocrangon_ (Fig. 110) with numerous species entirely confined to deep water. =Fam. 10. Crangonidae.=—The first pair of legs are subchelate, the carpus of the second pair is not subdivided, and the rostrum is short. _Crangon vulgaris_ is the common Shrimp of the North Sea. =Tribe 5. Loricata.= [Illustration: FIG. 111.—Dorsal view of _Scyllarus arctus_, × ½. (From an original figure prepared for Professor Weldon.) ] [Illustration: FIG. 112.—Embryonic area of developing _Palinurus quadricornis._ _Ab.1_, 1st abdominal segment; _E_, compound eye; _E′_, median simple eye; _L_, upper lip; _L′_, lower lip; _M_, mandible; _Mx.1_, _Mx.2_, 1st and 2nd maxillae; _Mxp.1_, 1st maxillipede; _T_, 6th (antepenultimate) thoracic appendage. (After Claus.) ] The Loricata include the Langouste (_Palinurus_) of the Mediterranean coasts, which replaces there the Lobster of the North Sea as an article of food, and the peculiarly shaped _Scyllarus arctus_ (Fig. 111), which is also prized in the Mediterranean as a delicacy. The bright red “Crayfishes,” _Panulirus_ and _Iasus_, of the Australian coasts are also largely used as food. Besides its peculiarity in shape, _S. arctus_ has remarkable scales on the second antennae in place of flagella. The larva hatches out as the so-called Phyllosoma, which must be regarded as a greatly flattened and modified[139] Mysis stage. [Illustration: FIG. 113.—Phyllosoma larva of _Palinurus_, sp. × 5. _Ab_, Abdomen; _Mxp_, 3rd maxillipede; _T_, antepenultimate (6th) thoracic appendage. (After Claus.) ]