Miscellaneous. 233 



On a neiv Subclass of Fossil Birds (Odontornithes). 

 By 0. C. Maksh. 



The remarkable extinct birds with biconcave vertebrae (Ichthyor- 

 nidfe), 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 kno^vn 

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

 dispa?', 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 nume- 

 rous, 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 united at the symphysis ; they are abruptly truncated 

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

 esjiecially 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 elon- 

 gated cannot at present be determined ; but the last vertebra of the 

 sacrum was unusually large. 



This 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. 



When the remains of this species were first described, the portions 

 of lower jaws found with them were regarded by the writer as repti- 

 lian t ; the possibility of their forming part df the same skeleton, 

 although considered at the time, was not deemed sufficiently strong 

 to be i^laced on record. On subsequentlj- removing the surrounding 

 shale, the skuU and additional j^ortions of both jaws were brouglat to 

 light, so that there cannot now be a reasonable doubt that all are 

 parts of the same bird. The possession of teeth and biconcave ver- 

 tebrae, although the rest of the skeleton is entirclj- avian in type, 

 obviously implies that these remains cannot be placed in the present 



* Amer. Journ. of Sci. and Arts, vol. iv. p. 344, Oct. 1872, and vol. v. 

 p. 74, Jan. 1873. 'Annals,' Jan. 1873, j). 80. 



t Amer. Journ. of Sci. and Arts, vol. iv. p. 406, Nov. 1872. 



