334 



THE AMERICAN NATURALIST 



[Vol. XLI 



ZOOLOGY 



Palms and Soles. — Dr. Schlaginhaufen of Dresden has written a 

 brief description of the palms and soles of man and the apes, based 

 upon a hterature of one hundred and fourteen publications.^ The 

 volar surface of the hand and fingers, and the plantar surface of the 

 foot and toes are thickly covered with slender ridges, the cristae cutis, 

 separated from one another by depressions, the sulci cutis. Along 

 the summit of a ridge, a row of SAveat glands opens. A primitive stage 

 in the formation of the ridges is seen in the Prosimiae, which have 

 small round elevations (insulae primariae) surrounding single sweat 

 pores. Besides these primary islands there are larger elliptical forms 

 on which several sweat pores may be arranged in a circle or ellipse, 

 surrounding a central depression. These lenticular islands are due 

 to the coalescence of primary islands radially arranged. A crista 

 is formed by the coalescence of a linear series. The minutiae of the 

 cristae, upon which personal identification depends, consist in the 

 branches of the ridges, which may end blindly or anastomose; in 

 detached ridges; and in the ridge patterns. The two principal 

 patterns are the more or less concentric tactile figures, and tli(^ Y shaped 

 groups called triradii. 



Besides the bas-relief of cristae, palms and soles pn sc nt the liiiiii 

 relief of tactile cushions, toruli tactiles. For each extrtMuity tlifit- are 

 typically five digital cushions at the tips of the firigers or toes; four 

 interdigitnl riis/n'ons near the metacarpo- or metatarso-phalangeal 

 joints; and two or tlin r proximal cushions, — a tibial and an elongated 

 fibular, or a radial and two ulnar, one behind the other. This ar- 

 rangement is typical for pentadactylous mammals and the cushions 

 are well developed in marsupials, rodents, the insectivora and pri- 

 mates. Often the interdigital cushions fuse, as in the cat, and that 

 between the thumb and fingers may be suppressed. Secondary 

 cushions are not infrequent — such as a central cushion found in 

 Cebus — but none occur in the anthropoid apes or in man. Cushions 

 are accumulations of connective tissue and are not to be confounded 



» Schlaginhaufen, O. t)ber das Lri.tcnivliri .l. r lIolilha.Ml- un.i I-u^^^.>hl('n- 

 Flache der Halbaffen, Affen und Mcnx hctira-M n. /• /,/,/-// ,/. A, ml. >,. luitir.. 

 vol. 15, pp. 628-662. Since writing this n-vicw, thv editor luts n-<riv..d the 

 announcement of the following book. Kidd, \N'. Th srn.sr of touch in mam- 

 mals and birds wUh special reference to the papillary ridtjes. London, A. and 

 C. Black, 1907. 8vo., 174 figs. 5s. 



