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POPULAR SCIENCE REVIEW. 
pelago. The centrodorsal is a flat plate, nearly on a level with the surface 
of the radials, or sometimes even below them, separated from them by clefts 
at its sides, and entirely devoid, not only of cirrhi, but also of cirrhus-sockets. 
This condition is only an extreme stage of the metamorphosis of the centro- 
dorsal piece, which bears cirrhi for a time after its liberation from the larval 
stem ; but these cirrhi eventually disappear and their sockets become obli- 
terated. The Challenger collection contains a series of specimens of Act. Jukesii, 
from Torres Straits, which illustrate this point very completely ; and it is, 
therefore, of no small interest to find a fossil Comatula which shows one of 
the extreme stages of the metamorphosis. 
The large size of the three Antedon species from the Chalk and Gault is 
very remarkable. Ant. paradoxus has a centrodorsal half as wide again as 
that of any recent form ; while Ant. Eschrichtii is the only recent species with 
a centrodorsal approaching the size of those of the other Chalk Antedon, and 
of that from the Gault. Act. Loveni, from the Gault, however, and the 
older Comatulae, all had small calices like most recent species. An elegant 
centrodorsal {Ant. rotundus) is described from the Haldon Greensand, and 
also two species from the Bradford Clay. One is an Antedon, the oldest 
known, with no special characters ; the other is an Actinometra, with a 
a centrodorsal essentially like those of species now living in shallow water in 
the Philippines and Malay Archipelago. The oldest known Comatula, an 
Actinometra from the Bath Oolite, has similar relations. 
Argillornis longipennis . — Some two years ago Professor Owen described 
before the Geological Society the humerus of a large bird from the London 
Clay of Sheppey, for which he proposed the above name (see Popular Science 
Review, New Series, Vol. ii., p. 106). Pie was inclined from the first to 
regard this bone as belonging to the wing of a large aquatic bird ; and the 
recent discovery of a portion of a bird’s skull in the same deposit would 
seem to be confirmatory of Professor Owen’s views. In this specimen, which 
was described by the Professor before the Geological Society, on the 5th 
November, the lower jaw and the fore-part of the upper jaw are deficient; 
and the characters presented by it, like those of the humerus previously 
described, were said to approximate the fossil most nearly to the Albatross 
among existing birds, although, like Odontopteryx, it differed from Diomedea , 
and also from the Cormorant and the Totipalmates generally, in the absence 
of the basirostral external nares and of the supraorbital gland-pits. The 
present fossil differs from Odontopteryx in having the fore-part of the frontal 
broader and the upper tract of the bill less defined, as also in some other 
characters ; but no comparison of the palatal structure can be made upon 
the existing specimens. In point of size, taking the Albatross as a term of 
comparison, this skull may well have belonged to a bird with wings of the 
extent indicated by the humerus already described ; and the resemblance of 
the skull to that of the Albatross would also seem to be confirmatory of the 
specific collocation of the two specimens. The presence of four small pits 
or perforations on the only part of the alveolar border which appears to be 
uninjured, led the author to conjecture that the bird may have been denti- 
gerous ; but this seems to be very uncertain. 
