196 R. M. Bry done— Chalk Polysoa. 



very slightly concave posterior face of the shaft; the trochlear surface 

 of the inner condyle {i.e.) extends a little higher up than that of the 

 outer. The fossa on the anterior face of the shaft is bounded internally 

 by a slight ridge, while on its outer side there is a strong flattened 

 ridge (?•.) running obliquely down to the upper border of the outer 

 condyle, and perforated hj a very narrow passage directed obliquely 

 downwards and inwards. This passage is too narrow to represent 

 the channel for the extensor tendons, present in most birds, and 

 moreover is not in the right position. A similar foramen is present 

 in many birds of very diffei'ent groups, e.g. Didiis and Dinornis; 

 probably it transmitted a blood-vessel. The outer face of the 

 external condyle bears a deep rounded fossa towards its anterior 

 border, and behind this there is a nai'row deeply cut pit, both 

 probably serving for the attachment of strong ligaments. The inner 

 face of the inner condyle is also excavated for the attachment of 

 ligament, but the cavity is comparatively large and shallow. Above 

 the inner condyle on the side of the shaft there is a roughened 

 depression for the attachment of a muscle. No very closely similar 

 form of tibio-tarsus has been found among recent birds. The 

 fact that the condyles are nearly equal in size and that one does 

 not project below the other separates this tibia widely from 

 that of Phalocrocorax, and gives the impression that the bird was 

 not adapted for swimming, but was ambulatory. It is of course 

 uncertain whether this tibia belongs to the same bird as the femora 

 described above, but from the close similarity of the sculpturing of 

 the surface of the bone in the two cases it seems most probable that 

 this is the case. If that is so, the resemblances found to exist 

 between the femur of Elopteryx and that of Phalocrocorax lose some of 

 their value, and it appears possible that the deep muscle impressions 

 on the trochanter of the femur, though indicating a very powerful 

 limb, do not necessarily point to an aquatic mode of life. Much 

 more material must be obtained before it is possible to ascertain the 

 affinities of Elopteryx, but that a large bird existed in Transsylvania 

 at the close of the Secondary period and in association with 

 Mochlodon, Tehnatosaurus, and other Dinosaurs is certain. It is not 

 the occurrence of birds at this horizon that is remarkable, but the 

 extreme rarity of their remains, while their complete absence from 

 such deposits as the Purbeck and Wealden is still more extraordinary. 

 The few remains that have been found in the later Secondaiy rocks 

 show that the group was already highly differentiated, and in the 

 Eocene pi'obably all the chief orders now existing were already 

 established. 



II. — Notes on new ok impekfecti-t known Chalk Poltzoa. 



By E. M. Brydone, F.G.S. 



{Continued from the March Ntimber, p. 99.) 



(PLATE VII.) 



rpHERE are a number of simple Cheilostomata which develop 



JL avicularia distinctly larger than the zooecia and more or less 



constricted in the middle by prominent masses apparently due to 



