190 BRITISH FOSSIL CRUSTACEA. 



{coxa, 1) is of great transverse extent, and besides affording insertion to the apodernal 

 muscles, which forcibly work the carding-plate, or ' palpus ' (PI. XXXIV, figs. 2 — 5, p), 

 gives origin to muscles acting on the second joint or c basis ' {jib., ib., 2). 



" Extensor basis pedis. — One of these, of small size, is an extensor of the ' basis ' 

 (PL XXXIV, fig. 5, a), but only in a slight degree. 



"The 'flexor basis' (ib., b) is a larger, especially broader, muscle, and bends the 

 ' basis ' forcibly upon the ' coxa ' or first joint. 



" Flexor merii cnemiique. — The muscle (ib., d) arising from the ' basis ' (2) is 

 supplemented by other fibres from the ' merion ' or third joint (3), proceeding penniforni- 

 wise to an entapophysis (c), attached to the base of the ' cnemion ' or fourth joint (4). 

 The action of this series of fibres is to bend both merion and cnemion. An ' extensor of 

 the cnemion ' is feebly developed. 



" Flexor propedis. — The cavity of the cnemion is chiefly occupied by tjie penniform 

 flexor (/) of the ' propes ' (5), upon which it acts chiefly through the medium of the 

 ' apodeme ' (e), attached to the base of that joint. 



" Flexor dactyli. — In like manner the penniform muscle, in the swollen basis of the 

 ' propes/ draws, through the medium of the entapophysis (g), the ' dactylus ' (6), power- 

 fully, in contact with the claw-like process of the 'propes' (5). 



" In the ' propes,' or fifth joint of the maxilliped, fasciculi of the muscular fibres are 

 grouped to be inserted into the short basal apophyses of the lamelliform appendages 

 (PI. XXXIV, fig. 4, 6), which they tend to approximate, or to close upon or around the 

 terminal chela (ib., 7). These plates, which radiate from the end of the * propes ' like the 

 petals of a flower, are expanded by being pressed against the mud or sand, and seem to 

 require muscles only for closing them, so as to facilitate the withdrawal of the limb. 



" The application of the maxillipeds in locomotion was observed by W. A. Lloyd, 

 Esq., the constructor of the aquarium at Hamburgh, of which he was for some years the 

 conservator, and subsequently the constructor of that at the Crystal Palace, of which 

 aquarium he is now the manager. 



" At Hamburgh, specimens of Limuli were kept alive from the year 1865 to 1870. 

 From his observations of these Mr. Lloyd informs me, ' the ulterior pair of limbs ' 

 (maxillipeds, vn) ' are not employed for walking, but exclusively for burrowing. These 

 limbs are terminated by four long, stiff, oval, or leaf-shaped lobes, jointed at their base 

 to the leg, and capable of being opened and closed in a four-radiate manner. When it 

 wishes to burrow these two limbs are sometimes alternately and sometimes simultaneously 

 thrust backwards below the carapace quite beyond the hinder edge of the shell, and in 

 the act of thrusting the lobes or plates on each leg encounter the sand, the resistance or 

 pressure of which causes them to open and fill with sand, a load of which at every 

 thrusting operation is pushed away from under the crab, and deposited outside the 

 carapace. The four plates then close, and are withdrawn closed, previously to being 

 opened and charged with another load of sand, and at the deposit of every load the 



