On the Structure and Development of the Hyobranchial Skeleton of the Parsley‐Frog ( Pelodytes punctatus).

Summary The almost complete closure of the hyoglossal sinus of Pelodytes (Jgs. , fig. 9) is due to the extensive development and inward slope of the processus anteriores ( pa. , fig. 9). The lateral foramina of Pelodytes (fl. , fig. 9) are not primary fenestrations of the basal plate, but are formed by the enclosure of the foremost lateral sinus by the confluence of the expanded end of the processus antero‐lateralis with the cartilage of the hyoidean cornu. Although in Pelodytes the hyoidean cornu ( h, h‘, h“ , fig. 9) is broken, the portion missing is comparatively insignificant. The spicula (sp. , fig. 1) are larVal structures of no morphological significance. They are processes of cartilage developed from the proximal ends of the ceratohranchials to support the horizontal pharyngeal velum. The processus postero‐lateralis ( ppl. , fig. 9) ia the persistent proximal portion of the first ceratobranchial. The processus antero‐lateralis ( pal. , figs. 8& 9) is a secondary outgrowth of the basal plate or body of the hyoid having no relation whatever to the larval branchial bars. The thyrohyal ( t. , fig. 9) is the part of the hypobranchial plate of the larva which forms the inner boundary of the thyroid foramen ( tf. , fig. 4). Its posterior end becomes free on the absorption of the ceratohranchials and the consequent conversion of the foramen into a sinus.