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Show 1897.] SKELETON OF PELODYTES PUNCTATUS. 585 proximal ends and the consequent angle which they make with the plane of the hypobranchial plate, it requires very careful observation to demonstrate the fact in this region. The only fibrous connection is that between the first and second ceratobranchials just anterior to the second spicule. The spicular cartilages are definitely continuous with the cartilage of the ceratobranchials, and do not give one the impression of their having arisen independently. These spicules (I have adopted Gaupp's name for these processes) of the Anuran larva have been the subject of a good deal of controversy by reason of the interpretation which Parker put upon them in his third contribution to our knowledge of the skull of Batrachia (12). I have already in an earlier communication (16. p. 113) expressed m y views on the subject and do not propose to discuss the matter farther. M y observations on the specimens which form the subject of this paper tend to confirm the view of Gaupp (5. p. 408), that the spicules have no morphological value, but that they are merely processes of cartilage developed from the proximal ends of the ceratobranchials to support the horizontal fold or velum which covers over the anterior half of the branchial cavity, and which undergoes reduction at the same rate as the spicules. The mandible is quite diminutive, and consists of four subequal cartilages. The median pair of these (m, fig. 1) carry the lower horny beak, the lateral pair (m1) are articulated with tbe palato-quadrate cartilage. STAGE 2. Distance from snout to root of tail, 20 mm. Tail at its maximum development, 28 mm. In length. Length of hind limb, extended, 21 mm. Fore limb not yet extended. Horny beaks still present. (Plate X X X V . fig. 2.) But few differences are to be noted between this and the preceding stage. The whole skeleton is considerably larger, the hyoglossal notch is more rounded than before, and the four constituent cartilages of the mandible are beginning to straighten out. Except for these features the description already given of the hyobranchial skeleton in the first stage would apply equally well in this Stage 2. In fact, m y chief object in introducing this into the series was to show that the hyobranchial skeleton attains its maximum larval dimensions without any appreciable change in shape. STAGE 3. Distance from snout to root of tail, 16 mm. Length of tail, 20 mm. Length of hind limb, extended, 19 mm. Length of fore limb, extended, 8 mm. Horny beaks no longer present. (Plate X X X V . fig. 3.) * The metamorphosis of the hyobranchial skeleton is now 1 I have here given the measurements of the specimen the hyobranchial skeleton of which is shown in fig. 3. It will be observed that the specimen is smaller than the average ; but if all the above measurements be multiplied by f the figures will be seen to be intermediate between those of the specimens chosen to represent Stages 2 and 4. |