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Show 66 DR. H. GADOW ON THE SUCTORIAL [Feb. 20, In the next stage E, the right and left halves separate into secondary tubes through the fissures at g and h becoming completed. The curling inwards of the free edges leads to the formation of four more or less complete secondary tubes, two external and two median. Each of these four tubes divides again on its median line ; and thus are formed eight tertiary, or perhaps rather four double tubes. These latter tubes break up again and again, but without forming new tubes, forming only the so-called brush of the tongue. This consists of about 80 or more horny bristles in Prosthemadera. A similar arrangement is met with in the few other Meliphagina which I have been enabled to examine, viz. Mohoa, Anthornis, and Meliphaga. The most important differences between the Nectariniina and Meliphagina in regard to the horny part of the tongue are therefore, first, that the tongue in the former does not form more than two tubes, whilst in the latter it is broken up dichotomously into 2, 4, 8, etc.; secondly, that in the Meliphagina it is always the external border of every tube that becomes laciniated, but in the Nectariniinos it is the inner or median border, whilst the external margin remains entire. In the Trochilida we meet with a third sort of tubular tongue. The tongue of these birds is double right down to the unpaired part of the os entoglossum, whilst each of the two distal prolongations of the entoglossal bone or cartilage is surrounded by a horny sheath, which is curled upwards and inwards, in a similar fashion to what we have seen in the Nectariniince. In many species the outer and inner edges of these tubes, however, are entire, and not laciniated. Thus the Trochilida? have developed the highest form of tubular tongue. The Muscles of the Tongue. NECTARINIA SPLENDIDA. M. mylo-kyoideus. This muscle fills the distal two thirds of the mandibular space; it arises from the inner aspect of the mandibles, and throughout its length fuses with its fellow of the other side. Its fibres run in a transverse direction. Near the anterior margin of the serpi-hyoid muscles, the mylo-hyoid is doubled up and is inserted into the soft and transversely wrinkled outer sheath of the basal part of the tongue proper (Plate X V I . fig. 1). M. serpi-hyoideus is the most superficial of the muscles of the hyoid apparatus. It occupies the basal or proximal half of the space between the mandibles; it arises as a narrow semitendinous slip from the posterior and upper angle of the processus serpiformis mandibula? immediately behind the masseter muscles. Its fibres are directed obliquely forwards and downwards, fusing with those from the other side in the middle line, without, however, forming a distinct linea tendinea. The anterior most distal part of this muscle is partly attached to the basihyal bone and to the sides of the stylohyoid muscle near its insertion. Whether these little lateral slips of |