14 



MINOT ON THE TONGUE 



portions and enters the tip. The upper surface of the tip has a deep frontal fissure, and 

 is thrown into fine transverse folds, behind which is a broad flattened median dorsal ridge ; 

 fig. 2, a, narrow posteriorly but widening frontwards. Duvernoy (V, p. 11), considered 

 this ridge {dm. his figure H) to be the posterior extension of the glandular portion, but 

 in G. dilepis it is entirely muscular. 



A transverse section, through the line 2, of fig. 2*, is represented in the accompanying 

 cut o. The whole upper half is strongly pigmented. The extension H, of the hyoid 

 occupies the centre of the lower part of the section ; its structure is noteworthy. Its core 



is composed of loose parenchymatous tissue, somewhat 

 resembling that of the vertebrate chorda dorsalis, in 

 that it consists of thick walled cells, having only a very 

 loose sarcodic network, and a protoplasma " Sof" 

 around the nucleus. A similar tissue fills, as will 

 presently be described, the hyoid bones and cartilages 

 of the mocking bird (llimus liohjgloUus). The ques- 

 tion therefore arises, whether this form of the medulla 

 ossi'um is general among the Sauropsida. Around the 

 pai'enchymatous core is a sheath of circular fibres or 

 perhaps elongated cells. Outside of this follows a layer 

 of longitudinal fibres, which from their distinctness 

 and considerable diameter, I at first thouy-ht miffht 

 be muscular, but I could not observe any striae, or 

 indications of fibrillar structure, so that I am uncer- 

 tain as to their nature. Entirely surrounding this layer is a thick fibrillar sheath. 

 The extension of the hyoid therefore consists of four parts. It lies in a distinct space, 

 apparently, though perhaps not really, a cavity, which is limited by a fibrous wall, that 

 gives rise to two obliquely radiating systems of muscular fibres, M, forming a thick cylin- 

 der, Duvernoy's "muscle anmdaire," which is not composed of circular fibres as he 

 believed. Upon the outside, as upon the inside, this cylinder is bounded by a connective 

 fibrous sheath, which gives insertion to the muscular fibres. These last have a disposition 

 for which I know no parallel whatsoever. At every point they are inclined to the radius of 

 the cylinder at about 40°, one set to one, the other to the other side. Moreover, the 

 fibres form laminae, each consisting of a single row of curving fibres, all nearly parallel 

 and of uniform thickness, not only between themselves, but also throughout the length of 

 each fibre. Finally, the laminae do not extend at right angles to the axis of the cylinder, 

 but lie in oblique planes. What advantage this extraordinary arrangement offers, I am 

 unable to suggest. 



There are four distinct longitudinal muscles, two large ones, I', at the sides of the cylin- 

 der, and two smaller ones I", above the cylinder, and below the ridge A. The fii'st one 

 probably the cerato-glossi, the latter perhaps the homologues of the 31. hyoglossi of 

 birds. A few circular fibres, c, lie at either side directly under the dermis, and spread out 

 above ^he large longitudinal muscles. 



The ridge. A, is separated by a layer of transverse fibres of connective tissue, and is 

 entirely occupied by a double system of curving muscular fibres, each of uniform thick- 



CuT 3. Transverse section of tiie tongue of 

 Chamntletm diU'pls, through the line 2, Fig. 1. A, 

 dorsal ridge; /', I" , longitudinal muscles; c, cir- 

 cular muscles; w! muscular cylinder around the 

 hyoid, H. X 12 diain. 



