^4 MR. W. K. PARKER ON THE OSTEOLOGY OF BAL^NICEPS REX. 



margin of these passages, formed by the nasal, is rough, and their hony roof about a 

 line thick ; the lower, formed partly by the same bone, is smoother, but strongly grooved 

 by vessels ; whilst the posterior boundary of the fossa is curiously scooped, the upper 

 scooped concavity being small, and the lower large, and reaching to within one-third 

 of an inch of the orbit. The actual nasal passage is less than half an inch long, and 

 one-sixth of an inch broad ; but the grooved and scooped parts of the osseous boundary 

 beneath project both behind and in front of it, so as to make its vestibular part full 

 an inch long. The nasal fossae and passages in Cancroma are very similar to these 

 structures in the Balreniceps, save that they are relatively larger, and the surrounding 

 parts composed of thinner and smoother bone. In the Heron, the nasal passages, which 

 freely open into each other, are actually longer than in the Balaeniceps ; and in the 

 Adjutant they are not so wide, but are twice as long. 



The large, well-made nostrils in Balseniceps have no affinity with those of the Pele- 

 caninse, which are extremely small, and actually become obsolete in the adult of some 

 species, e. g. the Cormorant. 



Prcs-maxilla. (PI. LXV. figs. 1, 6, & 7, pmx.) 

 Fishes are curiously like birds in the condition of their proper maxillary bones, the 

 'ossa mystacea,' which were not for some time recognized as the true homologues of 

 the mammalian and reptilian maxillaries. In most typical fishes they are above and 

 behind the dentary margin of the inter-maxillaries, and are themselves edentulous, — 

 the exceptions being in the Salmonidse, Sudis, &c. Passing from the study of any ordi- 

 nary mammal, or from the Chelonia or Crocodilia to Balaniceps, it would seem at first 

 blush difficult to put down nine-tenths of the huge face of the latter to the pre-maxillary 

 elements ; yet such is apparently the fact. Nor is this bird exceptional, for in all the 

 Gallinae the maxillary bones are, as in most typical fishes, above and behind the dentary 

 margin ; and they are relatively small in all typical birds. We have, however, as in 

 the class of Fishes, some instructive exceptions. In the Rhea, a bird whose nasals meet 

 at the mid-line, and in which the sacrum is, much of it, as abortively developed as in 

 the Frog, the maxillaries form half the region of the ' hard palate ' and one-third of the 

 dentary margin. In the Emeu {Dromaius ater) a similar state of things exists, save 

 that the premaxillary sends a long posterior, angular process, which hides the large 

 maxillary laterally. The rest of the Struthionidae are more or less like the Rhea and 

 the Emeu in this respect. We have also a similar state of things in the smaller genera 

 of the Fissirostres, as may be seen in the Common Goatsucker {Caprimulcjus europceus) 

 if examined when quite young. In this bird two-thirds of the palatal region and one- 

 third of the dentary margin are formed by the superior maxillary bone. In the Duck, 

 about half of the margin is maxillary. 



It was thought necessary to premise these remarks before passing on to describe the 

 rest of the Balaeniceps' face. Certainly a large amount of territory has this same pre- 



