226 . Prof. J. C. Schiódte on the Morphology 
developed by Latreile. Later zootomists and systematic 
authors, particularly Spinola and Erichson, have certainly 
occasionally turned their attention to the coxze of Eleutherata, 
and distinguished between coxs globose, transverse, an 
conice. But these distinctions, which only take into consi- 
deration the external form, are in themselves superficial, and 
lack the desirable sharpness and certainty of application, even 
when considered from the merely descriptive and diagnostic 
point of view—because coxe globose, by a gradual elongation 
downward, insensibly become coxe conice, and by lateral 
extension at last coincide with cox transverse, whilst the 
latter, when inclined inwards and downwards, become undi- 
stinguishable from coxæ conice. sides, cox: of each of 
these forms may be more or less moveable, and there is an 
insensible transition between those which are deeply inserted 
into sockets of articulation and those which are more super- 
ficially fixed; in consequence of which the distinction which 
now and then is made between coxe fixe and coxe mobiles, 
not only does not state any thing about the mode of movement, 
but is without connexion with the distinctions made with re- 
gard to form. These distinctions, therefore, however useful 
they may be within a limited systematic division, do not touch 
the central point of the question, which I hope to be able to 
place in a clear light by the following considerations. 
The limbs of Articulata articulate with the body in two 
principal ways, corresponding to two fundamental forms of 
coxe—coxe cardinate and core rotatorie. 
accommodate the muscles which move the remainder of the 
' leg, becomes more expanded and capacious in the same pro- 
portion. Where powerful movements are executed in a hori- 
zontal plane, by which the leg at the same time describes a 
€ are, particularly in running or swimming, the large coxa 
is shed with a groove (scrobiculus femoralis) on its ex- 
s as in order to obtain space for the bending forward 
of the leg. 
` Coxæ rotatorie can be turned round their own longitudinal 
* This ression is borrowed from Vitruvius (in the r “ De aliis 
Ear Si ' Schneider's edition, i. 301). n vue 
