The anatomy of the hand of certain insectivores

Abstract

1 Graphical reconstructions were studied from serial sections of the hands of Ptilocercus, Tupaia, Elephantulus and Crocidura 2 In all these insectivores and in Erinaceus the contrahentes and flexores breves profundi arise by a common fibrous sheet from the distal row of carpal bones, and have no metacarpal attachment. 3 The presence of this specialization suggests that the Insectivora constitute a, natural group. 4 Crocidura and other Soricidae have a complete set of smooth palmar, pads, and carpal vibrissae are developed, but many short palmer muscles have been lost. 5 The pollex is dwarfed in Elephantulus as in other Macroscelididae, and the thenar pads have been lost, but a full set of palmar muscles is retained. 6 The striation of the pads and the presence of raphés between the contrahentes in the Tupaiidae are probably arboreal specializations. 7 While the primitive eutherian hand probably resembled that of Crocidura in outward appearance, its musculature resembled that of Elephantulus, except that the flexores breves profundi arose from the metacarpals. 8 Hand anatomy constitutes no evidence either for or against the association of the Tupaiidae end Macroscelididae in a single suborder (Menotyphla) but divergent specialization of the contrahentes excludes any close association of the Tupaiidae with the Lemuridae.