THE SKULL IN THE WOODPECKERS AND WRYNECKS. 11 



strong, and the orbits well marked ; the interorbital space is small ; the lachrymal is a 

 little bone attached to the nasal. The exoccipital and basitemporal together, with the 

 help of about three tympanies, that soon coalesce, form the most curious tympanum seen 

 in the class ; it is like a cowrie shell : the Duck comes nearest to the Pici in this 

 respect. Even with materials at hand, I cannot go further into the skull, as the fore 

 face is at present my proper field. 



Since the above description of the skull of the fledglings and the adult Green Wood- 

 pecker were written, Samuel Whitbread, Esq., E.P.S., has sent* me & first-autumn spe- 

 cimen of this kind ; and this stage happily bridges over the great distance between the 

 fledgling and the old bird. Its description may well come in after that of the adult 

 skull ; for it serves as a most perfect key to the mysteriously complex basketwork of the 

 old bird's palate, and also sheds a clear light upon the embryo-passerine characters seen in 

 these birds. 



The progress of anchylosis through the five additional months has been intense, and 

 many new parts have appeared. This is in conformity with what was observed in the 

 Eowl, many of the metamorphic changes taking place during the first year, although so 

 much had been gone through in the egg. 



The anterior trabecular splints, the prsemaxillaries (Plate II. fig. 6,px), have coalesced 

 with the palatines and maxillaries ; and the appearance of free ends to their palatine 

 processes, well seen in Picus minor (Plate IV. fig. 1, p.sp.x), does not appear to be the 

 case here, the retral snags being due in the Green Woodpecker to additional ossicles. 

 All the three membrane bones that lie near the septum, on each side, belong to the 

 vomerine series (vomers and " septo-maxillaries ") ; and those which had appeared on the 

 fledgling (Plate I. fig. 2, v, s.mx) have now attained their fullest free development. 

 Yet I cannot find the " posterior vomer " of the old bird here (Plate II. figs. 2-5, v"). 

 The series of " mediotrabecular splints " forms a long chain, reaching from the anterior 

 end of the prsenasal style (p.n) to the " ethmo-palatine laminae." 



Beginning at the hinder extremity of the series, we have the true symmorphs of the 

 vomerine crura of the Passerine bird (the " shoulders " of the compound bone I shall 

 describe presently) ; and only on the right side do I see any attempt at cutting off the 

 " posterior vomer " (Plate II. figs. 6 & 8 v"). 



These " free vomerine crura " are long, thin, half-coiled bones, convex outside, concave 

 within, thick below, sharp and serrate above. They do not reach their proper fastening- 

 point (the ethmo-palatines) behind, having become dislocated by growth (see Plate III. 

 figs. 5 & 6, v, for their primordial " Rhynchosaurian " position) f. 



Attached to the fore end of the vomer by fibrous tissue, is a somewhat slenderer 

 needle-shaped bone (Plate II. figs. 6 & 8, s.mx 5 ). This is the hindermost of the " septo- 

 maxillary chain ;" it undergirds the " inturned alinasal laminae " (i. a. I), to which it is 

 strongly tied by fibrous tissue. A similar bone, but still slenderer, is attached to the 



* This bird was sent from Sou thill (Biggleswade) on the 1st of November, 1872 ; it was a young of the first 

 autumn, and therefore half a year old. 



t Compare those figures of the youngest Green Woodpecker's vomer with Dr. Giinther's figures and descriptions 

 of Hatteria (Phil. Trans. 1S67, part ii. plate i. fig. 2, p. 5). 



c 2 



