OCR Text |
Show 2 8 8 MR. W. P. PYCRAFT ON THE [Mar. 17, which descends so as to lie between and force apart the maxillo-palatine, causing the palate to be indirectly desmognathous. In Turacus the nasal septum fuses with the dorsal borders of the maxillo-palatine, and does not descend between them, but in this case also the palate is indirectly desmognathous. In both Coua and Turacus, but for the septum, the palate would be schizo-gnathous. But the maxillo-palatine region in Schizorhis, for example, is practically identical with that of normal Cuculi. Coua has the least specialised palate among the Cuculi; Turacus among the Musophagi. In the more specialised skull of both groups indirect desmognathism appears to have taken place by the descent of the ventral border of the septum nasi between the maxillo-palatine processes; resulting in the formation of a flat palatal surface, or one with a slight median groove. The very striking differences in the form of the pelvic girdle stand in strong contrast with the uniformity found in the skull. How considerable these differences in the girdle are may be seen in the figures on pp. 277, 280, and 282. Finally, I may remark that a great deal yet remains to be done before our knowledge of the Osteology of this group is complete. Of the nestling skeleton of the Musophagi we know nothing, and only a very little concerning the early stages of the Cuculi. Only about one-third of the total number of genera of Cuculi are represented in the Museum Collection of skeletons. These, however, fortunately, include all the more important forms. x i. K e y to th e O steology of th e C u cu l ifo rm e s . A. S k u l l . Palate desmognathous, and without conspicuous anterior palatal vacuity ; nostrils holorhinal, imperforate; basipterygoid processes wanting; vomer vestigial or wanting; pterygoid free; lachrymal free; antorbital plate large; the postorbital process never extending down to the quadrato-jugal bar. A. Mesial border of palatines not meeting in middle line, leaving parasplienoidal rostrum exposed ; with a large os uncinatum ............................ M u s o p h a g i . B. Mesial border of palatines meeting in middle line below and concealing para-sphenoidal rostrum ................................................................................... C u c u l i . Key to the Genera of Cuculidse. a. Beak long and pointed. a'. Lachrymal with massive descending process; nostrils linear near the middle of the tomium; temporal fossae confined to lateral aspect of skull. Geococcyx. b'. Lachr}'mal very small; temporal fossa? meeting one another to form a broad sagittal crest ................................................................................. Saurothera. b. Beak with a high median keel; lachrymal large ................. Crotophaga. c. Beak swollen, with an arched culmen. e'. Palatines fused in median line posteriori}' .......................... Scythrops. d'. Palatines free posteriorly. a". Nostrils linear immediately above tomium ; postorbital process of lachrymal large....... ............ ................................................................ Rhamphococcyx. b". Nostrils oval immediately above base of tomium, and bounded above or confluent with a conspicuous fenestra; postorbital process of lachrymal small ........................................................................................... Rhinococcyx. ' |