. The annals and magazine of natural history : zoology, botany, and geology . ried by the berried female, that the young dohatch at an early stage, probably as a zocii or protozoea. 532 Miss G. E. Webb on some Tlie appendages in both these stages are typicallyBiuchyuran in character, the anteuiiular statocyst beingparticularly well-developed (fig. 2). Tlie chief feature ofinterest presented by the Megalopa is the size and positionof the last pair of thoracic legs. Tliese are much smallerthan tlie preceding pairs, and the inner margin of the lastjoint or dactylopodite is not serrate, as in the
. The annals and magazine of natural history : zoology, botany, and geology . ried by the berried female, that the young dohatch at an early stage, probably as a zocii or protozoea. 532 Miss G. E. Webb on some Tlie appendages in both these stages are typicallyBiuchyuran in character, the anteuiiular statocyst beingparticularly well-developed (fig. 2). Tlie chief feature ofinterest presented by the Megalopa is the size and positionof the last pair of thoracic legs. Tliese are much smallerthan tlie preceding pairs, and the inner margin of the lastjoint or dactylopodite is not serrate, as in the other claws,but quite smooth, and carries a terminal group of three longsetaj (fig. 1). This slender last pair of legs is more dorsalthan the others, and is carried bent forwards on the uppersurface of the carapace, often with the last three joints closelyflexed on the proximal joints. In the next stage (fig. 3) the fifth pair of legs is notnoticeably small in proportion to the other thoracic legs, nordoes it terminate in a group of setae ; it is, moreover, carried Fig. First young stage. Dorsal view. Length of carapace=4*2 mm. extended laterally in a normal position, no longer bent upover tlie back of the animal as in the preceding , therefore, tliis peculiar character of the fifth pairof legs is confined solely to the megalopa stage of the life-history; there is no trace of it in the adult crab. The small size and dorsal position of the fifth thoracic legsin the adult is a character which is typical of certain groupsamong the Brachyura. These are the Dromiacea; the Dorip-pidai and lianinidae among the Oxystomata; and thePalicidseand Ptenoplacidse among the Brachygnatha. It is not so easy to determine how common this feature isin the megalopa stage of the Brachyura, as the literature onthe larval stages is still very incomplete. It however, that the three main points comprised in Young Stages o/Gecarcoidea lalaiidii. 533 the modification, viz. tlie s
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