662 EEPOET— 1881, 



strongly resembles that in modern birds. All of the usual elements are present, 

 and most of them are distinctly a"vian, the furculum especially so. 



4. There are three digits only in the manus, all provided with claws. The 

 three free metacarpals have the form and position of those in some young modern 

 birds, and although corresponding to the same bones in reptiles, have the avian 

 stamp already upon them. 



5. The pelvic bones are separate. In this respect Ai-chceopteryx differs from all 

 adult birds recent and extinct, and agrees with Dinosaurian reptiles, a point of 

 much importance. Diagrams illustrating this were shown. 



6. The distal end of the tibula is placed in front of the tibia. This is not known 

 in any other birds, but is a characteristic of Dinosaurs. 



7. The metatarsal bones are separate, or imperfectly united. This chai-acter 

 also has not before been observed in any adult birds, modern or ancient, but is seen 

 in all known Dinosaurs. 



The author also stated that the brain-cast of Arch(eoptery.v resembled that of 

 Laopteryx, an American Jurassic bird, which he had recently described. The 

 brains of both appear to have been comparatively larger than in Hesperornis, 

 which may be due to the fact that they were land birds, while all known cre- 

 taceous birds were aquatic. 



The author considered the nearest allies to birds to be the Dinosaiu'ian reptiles, 

 which really constitute a sub-class rather than an order. Among these reptiles, 

 Comptognathus is especially bird-like in the extremities, but the vertebrte and 

 pelvis show important differences from all known birds. In examining the 

 original specimen of Cvmptoynathus in Mmiich, the author detected in the 

 abdominal cavity the skeleton of a young reptile, apparently a foetus, but possibly 

 one that had been swallowed. Nothing of the kind had before been noticed in 

 Dinosaurs. The presence of a clavicle in this group of reptiles had not hitherto 

 been determined, but two specimens of Iguanodon in the British Museum show 

 that this genus possessed these bones, and drawings of one were shown. The 

 relations of Dinosaurs to early forms of birds the author had discussed iu detail in 

 his memoir on the Odontornithes, published during the previous year. 



2. On the use of the Chitinous Elements or Appendages of the Cheilostoma- 

 tous Pohjzoa in the Diagnosis of Species.^ By George Busk, F.R.S. 



Having for some time been engaged in the description of the Polyzoa collected 

 on the Challenger Expedition, the author — in common, he believes, with all who 

 have made that class the subject of study — has been greatly perplexed to find satis- 

 factory distinctive characters in several of the natural groups composing it. Amongst 

 the most difficult and puzzling may be more especially mentioned the generic groups 

 comprised under the names of Oellepora, Retepora, and Cellaria or Salicornaria. 



As it is but quite recently that his attention has been directed to the use that 

 might be made of the chitinous appendages, in addition to those usually employed, 

 derived from the calcareous skeleton, he has not been able at present to extend 

 his observations beyond the three genera above mentioned, but he has little doubt 

 it will be found extremely useful in many others, more especially among the 

 Escharidre, 



His attention was first drawn to the use that might be made of the chitinous 

 organs by the perusal of a short paper by Mr. A. W. Waters, in the Transactions 

 of the Manchester Philosophical Society, on the use of the operculum as affording 

 difierential characters. 



Led by this valuable suggestion to see how far the character of the operculum 

 might assist him in the diagnosis of the species of Cellepora on which he was at the 

 time engaged, he was at once struck with the great facility that attention to this 

 character afibrded in the distinction of otherwise obscure forms of this most 

 difficult group. 



* Published in extenso in Linn, Soc. Journal, vol. sv. 



