39. The Comparative Anatomy of the Tongues of the Mammalia. – VI. Summary and Classification of the Tongues of the Primates.

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Summary.: .Pigmentation. – Most of the pigmented forms are included in the Cebidæ. The colour, which is yellow, green, brown or bluish‐black, especially the latter, is uniformly distributed all over the dorsum, or the pigmented and colourless parts may form definite patterns; in Ateles grisescens, for example, there is a white cross on a brown background. The vallate and fungiform papilæ may be pigmented (e. g. in Hylobates lar) or colourless, but the lateral organs and central parts of the inferior surface of the tongue are always white. If several examples of each pigmented species are examined it will be seen that the colour varies considerably, so is of no value for purposes of classification. Most specimens of Cercopithecus patas, for example, have reddish‐yellow tongues, but some tongues are colourless, and the fungiform papillæ of Cercopithecus tantalus are yellow or colourless.The bluish‐black colour persists longest in preserving fluids.Form and Proportions. – Most tongues are conical, but a few are oval, spatulate or rectangular; and shape is of no value for comparative purposes.In most of the Primates the tongue is long and comparatively narrow, but in Anthropopithecus troglodytes and Gorilla gorilla the tongue of the young animal is relatively wider than that of the adult. I did not, however, see such variations in Cercopithecus patas or Macacus sinicus, of which I examined very young and adult examples.Cunningham showed that the tongue of Simia satyrus resembles that of Homo most closely in the relative proportions of length and width.The Ape'is round, truncated or pointed, and may or may not have a notch, but the latter is usually absent from the fresh tongue. It is comparatively smooth, or roughened and tuberculated by small conical and fungiform papillæ. The relative quantities of fungiform papillæ on and immediately behind the apex vary; in the Simiidæ and Cercopithecidæ they are numerous and thickly clustered, but in the other families they are few and discrete.In some species of Lemur the apex exhibits a number of sharp‐pointed processes prolonged forwards from ridges on the inferior surface of the tongue, but these vary even in different examples of each species.Sulci and Ridges. – Few fresh tongues have median dorsal sulci on the oral part of the dorsum, but many preserved specimens‐ do; and I observed a well‐marked median sulcus on the pharyngeal part in Anthropopithecus troglodytes alone. The most pronounced mesial dorsal sulcus which I observed occurred in Mystax ursulus. Median dorsal ridges are present in some Lemuroidea, and Hapalidæ.Wide, shallow transverse sulci separating low wide transverse ridges are present on the fresh tongues of Lemur catta and Hapcde jacchus; and fine narrow sulci are seen in Gorilla gorilla and Perodicticus potto. Some of the fine sulci and ridges remind one of the patterns of fissures and ridges on the finger‐tips.The median ventral sulcus is present in most tongues, and is never an artefact induced by preserving fluids as is the dorsal one in bottled specimens. It is narrow and deep, or wide and shallow, and it frequently opens posteriorly into a triangular fossa which recieves the upper end of the frenum. In some of the Lemuroidea it receives the median dorsal crest of the sublingua, and it recesses the crest on the dorsal surface of the frenal lamella of Cebus fatuellus.In Gorilla gorilla, some species of Hylobates and some of the Lemuroidea it contains a fixed crest: and it has been stated that the crest is a remnant of the sublingua, but the presence of both these structures in some Lemurs would seem to disprove that theory.Lateral Borders. – The edges of the tongue are sharp, or full and rounded, and increase in thickness from before backwards in most species. Those of Chiromys niadagascariensis are more massive in proportion to the size of the tongue than those of any other species of the Primates. Of the Pithecoids Simia satyrus and Anthropopithecus have the most massive lateral borders.In Tarsius spectrum, Microcebus, Chiromys, and all Lorisidse and Galagidse the lateral borders are devoid of lateral organs and, as I hope to show in a future paper, this has an important bearing on phylogeny. In Gorilla gorilla and Simia satyrus only small parts of the lateral organs are found on the lateral borders, but in all other Primates the greater part is found there.The conical and fungiform papillæ on the lateral borders are arranged in vertical rows and the points of the former are directed backwards,Distribution of the Papillœ. – In all Primates except some specimens of Simia satyrus and Symphatamgus syndactylus, some Lemuroidea and Homo, papillæ cover the entire dorsum, apex, lateral borders, and a bounding zone of the inferior surface. In all these species there are smooth non‐papillary areas on the base‐of the tongue, and in the Lemurs the area is bisected by the median glosso‐epiglottic fold.The ventral papillary zone varies greatly in width, and its characters are of limited value for purposes of classification. It is wide in the Simiidse, Cercopithecidæ, and in Cebus, Ateles, and Lagothrix, but is narrow or absent in all other Primates. In species with a wide zone the conical and fungiform papillæ are numerous, but in those with a narrow zone there are few or no fungiforms. In Gorilla gorilla many of the fine transverse sulci on the dorsum cut the lateral borders and run inwards on the ventral papillary zone.The Circumvallate Papillœ. – In my paper on the tongues of the Cercopithecidæ I showed that all the papillary patterns present in the family will be seen in most species if sufficient examples of each are examined. The whole series may quickly appear or it may be necessary to examine many. I am not prepared, however, to apply this rule to any other...

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