178 UPPER, OR FLINTY CHALK. 



research, to whom I am under infinite obligations, for many valuable com- 

 munications on scientific subjects. 



Locahties. Upper chalk, near Lewes ; very rare. 



CHOANITES. 



Gen. Char. Form various, generally either funnel-shaped, spherical, 

 globular, or subcylindrical, having a central opening in the superior part ; 

 the original composed of a parenchymatous substance, capable of imbibi- 

 tion and contraction ; the base fixed. 



The fossil zoophytes which this genus is intended to comprehend, are 

 very numerous, and hold an intermediate place between the alcyonia, 

 properly so called, and the ventriculites. They are distinguished from the 

 former by the central cavity in their superior part, and from the latter, by 

 being destitute of an external reticulated integument, &c. and possessing 

 but a shght degree of contractile power. 



The alcyomum Jiciis of Linne {figure de suhstajice et d'eponge etd'alcion, 

 of MarsiUi) may be considered as the type of the genus. " It is of the 

 form of a fig, being attached to the rocks by branches proceeding from its 

 smaller end ; the upper part is a little flattened, and has a cavity in the 

 middle. Its colour resembles that of tobacco, and its parenchymatous 

 substance cannot be compared to any tiling better than to nutgalls when 

 well dried *." 



The fossil remains of this genus, (hitherto indiscriminately placed 

 among the alcyonia) were first noticed by M. Guettard at Verest, 

 and at Montrichard in Touraine, and form the subject of a paper 

 published in ihe Meinoirs of the Academy of Sciences at Paris (ann. 1757). 

 He observes, that they are of a globular form, having the base in many 

 examples elongated into a pedicle. In the centre of the superior part is 

 a circular opening, generally filled "with the substance in which the 

 fossils are imbedded. This cavity is larger in its upper than in its lower 

 part, and is continued almost to the pedicle, in some specimens appearing 



* Organic Remains, Vol. ii. p. 96. 



