200 ~~ Mr. R. Walker on Clays, containing Fossils, 
The Antipathes Larix which I had in my possession had its 
convolutions crammed with corpuscles resembling in transpa- 
rency and tint the testicular capsules of Gerardia. If it were 
not rash to come to any conclusion from observations made on 
objects not in the best possible state, I should say that the sexes 
are separate, and borne not only by distinct polypes, but even 
upon distinct polyparies. But [ cannot generalize and assert 
that this is always the case. 
The polypary of the true Antipathes bristles all over with 
spinules. These have not escaped other writers, but some of 
them have erroneously regarded them as abortive branches. The 
arrangement of these spines may furnish useful characters for 
the discrimination of the species. 
The sarcosoma everywhere covers the polypary, which appears 
as if enclosed in a sort of distinct sheath. When it contracts, its 
tissue is traversed by the spicules, as is the case in the Gorgonia. 
The growth of the polypary takes place by the deposition of 
layers which are superimposed upon the stems, and which at 
the extremities resemble the fingers of gloves enclosed one within 
the other. The centre of the axis appears to be perforated by a 
canal; but this is only an appearance due, in fresh individuals, 
to the inferior density of the substance which has been added at 
the extremities and become internal, and, in dried specimens, to 
the contraction of this substance. 
Between Gerardia and Antipathes there are great differences. 
In the former the polypary is smooth and covered with very 
small and scarcely sensible umbilicated elevations; in Anfz- 
pathes it is covered with spinules. The twenty-four tentacles of 
Gerardia correspond with as many chambers separated by the 
same number of septa with convoluted filaments ; in Antipathes 
only two of these convoluted cords are developed, and the tenta- 
cles are never more than six in number. In Gerardia the Acti- 
nian type is as highly developed and characterized as possible ; 
in Antipathes it remains incomplete, in consequence of a sort of 
arrest of development. 
XXIV.—On Clays, containing Fossils, near St. Andrews ; with 
Remarks on some of the latter. By Rospert WALKER. 
Tue Clay-bed whose geological position and fossil contents are 
about to be noticed is situated near the mouth of the Kinness 
Burn, or rivulet, a small stream that runs past St. Andrews on 
the south side. Towards the sea this stream has eroded its 
channel about three feet through the bed. At one time the 
clay could be seen forming part of the bank on each side of the 
