Notices of Memoirs. — Prof. 0. C. Marsh on Fossil Birds. 115 



Galt.^ a. (a) Fitton. (b) 1824. (c) An. Phil., vol. viii. p. 365. 

 {d) Clay of the Undercliff or Gault. (e) Gait is said to be 

 a local name. [Query — In what county or counties is it used 

 and in what sense? See Fitton, Geol. Journ., 2 ser. vol. iv. 

 p. 306, 1836.] 

 B. See supra. C. None. 



nsroTiciES OIF :]\d::Enyi:oiias. 



I. — On a New Sub-class of Fossil Bikds {OdontornitJies). By 

 Prof. 0. C. Marsh, Yale College, Ct., U.S.A. 



THE remarkable extinct birds with biconcave vertebrae {IcTithyor- 

 nid(s), recently described by the writer from the upper Cretaceous 

 shale of Kansas,^ prove on further investigation to possess some 

 additional characters, which separate them still more widely from all 

 known recent and fossil forms. The type species of this group, 

 Ichihyornis dispar, Marsh, had well developed teeth in both Jaws. 

 These teeth were quite numerous, and implanted in distinct sockets. 

 They were small, compressed and pointed, and all of those preserved 

 are similar. Those in the lower jaws number about twenty in each 

 ramus, and are all more or less inclined backward. The series 

 extends over the entire upper margin of the dentary bone, the front 

 tooth being very near the extremity. The maxillary teeth appear to 

 have been equally numerous, and essentially the same as those in the 

 mandible. 



The skull was of moderate size, and the eyes were placed well 

 forward. The lower jaws are long and slender, and the rami were 

 not closely imited at the symphysis. They are abruptly truncated 

 just behind the articulation for the quadrate. This extremity, and 

 especially its articulation, is very similar to that in some recent 

 aquatic birds. The jaws were apparently not encased in a horny 

 sheath. 



The scapular arch, and the bones of the wings and legs, all conform 

 closely to the true ornithic type. The sternum has a prominent 

 keel, and elongated grooves for the expanded coracoids. The wings 

 were large in proportion to the legs, and the humerus had an 

 extended radial crest. The metacarpals are united, as in ordinary 

 birds. The bones of the posterior extremities resemble those in 

 swimming birds. The vertebrae were all biconcave, the concavities 

 at each end of the centra being distinct, and nearly alike. Whether 

 the tail was elongated cannot at present be determined, but the last 

 vertebrae of the sacrum was unusually large. 



The bird was fully adult, and about as large as a pigeon. With 

 the exception of the skull, the bones do not appear to have been 

 pneumatic, although most of them are hollow. The species was 

 carnivorous, and probably aquatic. 



1 This is sometimes spelt Golt (as by Rev. J. Mitchell in his Table of Sequence, 

 nSS) and Gault. I believe Gait to be correct. 



2 Silliman's Journ., vol. iv. p. 344, Oct. 1872, and vol. v. p. 74, Jan., 1873. 



