13 



transverse extent, and besides affording insertion to the apodemal muscles, whicli forcibly- 

 work the carding-plate, or ' palpus ' (PL II a. figs. 2-5, p), gives origin to muscles acting 

 on the second joint or ' basis ' (J6. ib. 2). 



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

 (PI. II A. 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 cnemiiqne. — The muscle (/&. d) arising from the 'basis' (2) is supple- 

 mented by other fibres from the ' merion,' or third joint (3), proceeding penniform-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 the 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, throiigh the medium of the entapophysis, g, the dactylus, e, powerfu.Uy, 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. II A. fig. 4, 6, t), 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 Hambvirgh, specunens of Limtili were kept alive from the year 1865 to 1870. From 

 his observation of these Mr. Lloyd informs me, " The ulterior pair of limbs " (maxillipeds, 

 vii) " are not employed for walking, but exclusively for bm'rowing. These limbs are 

 terminated by four long stiff lobes of an oval or leaf-shape, jointed at the base, on 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 the 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 whole 

 animal sinks deeper into its bed, till it is hidden all except the eyes. The great hiding- 

 shield of a carapace again prevents one from seeing whether this excavating work is aided 

 by the fanning motion of the abdominal false feet, as is the case with the British Lobster ; 



