212 MR. W. K. PARKER ON THE OSTEOLOGY 



In the latter bird, in its relative the Dotterel (Charadrius hiaticula), and in not a few 

 of the " Grallse," the frontal in the young bird sends out square denticles of bony 

 substance under and beyond the gland ; they form beyond the gland a smooth eave to 

 the large eyeball ; this eave extends forwards to coalesce with the large orbital plate of 

 the lachrymal, and backwards to join the postfrontal process. In many Grallse and 

 Palmipeds this part is not developed, and the gland forms a thick edge to the eye- 

 brow. In the Lapwing and others that have the secondary frontal margin, the gland 

 is often but little protected beneath — the denticles not melting together, as a rule, 

 until they meet beyond the gland. Anteriorly it is better floored, and close inside the 

 lachrymal is the round passage for the efferent duct (PI. XXXVII. fig. 3, g.d.). In the 

 Tinamou we have not denticles, but ossicles — a whole row of superorbital bones, the like 

 of which must be scnight for, not amongst birds, but in a group of creatures a long 

 way down in the scale (PI. XL. fig. 2, sr.o.). My surprise at finding a perfect chain of 

 bones in this region (see Zool. Proc. 1862, pt. iii. p. 259) arose from my failing to 

 identify it with the row of dermal bones long familiar to me in the skull of the Blind- 

 worm {Anguis fragilis). I mentioned the three superorbitals over each eye of the 

 Trigonal Cayman ; but this instance does not satisfy the comparative anatomist nearly 

 so well as the Blindworm, or better still the Skink Lizard, e.g. Mocoa. The largest 

 of these square pieces is about 3 lines across, and is past the middle ; the anterior ones 

 are somewhat smaller, and the posterior, which run down to the postfrontal ossicle, 

 are very small (PI. XL. fig. 3). There are six main pieces on the right, and seven on 

 the left side, besides four or five additional grains behind. On their inner edge these 

 superorbitals are, like the frontal, scooped to receive the nasal gland ; but they do 

 not underlie all of it, and an open space (fig. 2) exists under the anterior half of the 

 gland : thus the same results are arrived at as in the Dotterel and Lapwing, but by 

 different means. The lachrymal (PI. XL. fig. 3, 1.) of the Tinamou is like that of the 

 Lapwing, its superorbital plate projecting even less than in that bird, and the 

 descending plate being relatively of the same size, and wanting the oval foramen of 

 the struthious lachrymal. What there is of the lachrymal in the Apteryx is still more 

 closely compressed, and is only flush with the rest of the face ; in the other " Struthio- 

 nidse " the superorbital process projects far backwards and outwards, like that of the 

 Falcons on one hand and the Safeguard Lizards {Monitor) on the other. This bony 

 fence to the opercular flaps of the great optic space is curiously like the skeleton of 

 the sense-organs themselves — the eyeballs ; it looks at first sight as though a half- 

 circle of the sclerotics had been falsely placed along the upper orbital eave. 



In typical birds, before they have attained their full size, the tympanies have often 

 a chain of five, and even, in the Carrion-Crow {Corvus corone), of six tympanies, — besides 

 an occasional development of a posterior meatus-bone attached to the tympanic wing 

 of the lateral occipital, as occurs at times in this same Crow, and constantly in the 

 Peafowl {Pavo cristatus). So that this superorbital series is, morphologically, quite 



