OCR Text |
Show 620 MR. E. B. POULTON ON THE [Dec. 18, into these by a lessening of the posterior cornified part until it ceases to differ from the rest of the ring. B. The Filiform Papilla are probably normal in structure, as they are in shape and position. Thus this tongue comes nearest to Perameles in the circumvallate papilla?, but is very peculiar in the coronate papilla?, and primitive in the possession of isolated hair-like papilla?. General Conclusions. The above observations may be shortly recapitulated, and the tongues of all the Marsupials yet examined may be classified as follows (the types are printed in italics): - I. A. Circumvallate papilla approximately identical, bilaterally symmetrical; much protected (the mouth of the involution probably capable of closure), and the pointed apex directed forward (exc). The taste-bulbs ascend high up the papillary sides in the most typical instances. Posterior angle very obtuse (exc). B. Lateral organ very primitive, and showing its origin as a row of gland-ducts. C. Coronate papilla with irregular circles of secondary papilla? (in some places). Intercalated single hair-like papilla? present. Halmaturus ; Macropus ; Petrogale ; Dasyurus (?). II. A. Circumvallate papilla.-The two anterior are smaller and of the type described above, although sometimes presenting the characters to a less degree; the posterior larger, and radially symmetrical ; the summit is a circular disk which can be seen from the surface; the whole papilla resembles that of the higher mammals (except for the constricted base). Posterior angle acute. B. Lateral organ.-Less primitive; an irregular row of slit-like furrows ; gland-ducts distinctly open at the bottom of the furrows. C. Coronate papilla less irregular; no intercalated hair-like papilla?. Phalangista ; Belideus ; Acrobates. III. A. Circumvallate papilla approximately identical and of the same type as the posterior papilla? of Division II. Posterior angle varies. B. Lateral organ absent. C. Coronate papillce very regular; no intercalated hair-like papilla?. Perameles; Didelphys ? (does not follow C ). It is very interesting (and I venture to think significant) that the structural features which combine together to make one of the abuve divisions show considerable correlation with one another. |