ALCIPPE LAMPAS. 539 



have borne the fourth pair of cirri,, at first sight falsely 

 appears like the terminal segment of the thorax : in one 

 monstrous specimen it bore a single cirrus, showing (if 

 there had been any doubt) that it was a true segment. 

 The three terminal pairs of articulated appendages, form 

 together a brush ; they consist of the fifth and sixth pairs 

 of cirri and of the caudal appendages : my reasons for 

 considering the last-named organs as of caudal origin will 

 be given hereafter. A moderately careful inspection, espe- 

 cially of the ventral surface, will show that the fifth pair of 

 cirri are borne on a small segment {n, fig. 5, but plainer 

 in fig. 13), which is quite distinct from, but partially con- 

 cealed by, that which ought to bear (and did bear in 

 the monstrous case) the fourth pair of cirri : this seg- 

 ment is oblique, and cannot be traced distinctly all round 

 the dorsal surface. The segment (o, fig. 13) bearing the 

 sixth pair is much less distinct, and can only be seen 

 by a longitudinal section, or when the cirri are a little 

 separated, but it certainly exists,* as is likewise shown by 

 the presence of small apodemes dipping in amongst the 

 muscles, between this and the last segment. The posterior 

 or caudal appendages are closely approximated; they are 

 not separated by any fold from the sixth thoracic segment ; 

 but appear as if they were articulated on the dorsal surface 

 of the sixth pair of cirri, in exactly the manner usual in 

 the other Lepadidse. The segments bearing the fifth and 

 sixth pairs of cirri are highly oblique to the preceding 

 segments, and consequently the cirri, which they support, 

 instead of projecting imvards, lie like a brush in a line 

 with the longitudinal axis of the main part of the thorax. 

 The membrane forming the two small oblique terminal seg- 

 ments of the thorax is strengthened by irregularly shaped 

 plates of thicker and yellowish membrane. 



Mouth. — The mouth is constructed on the strictly normal 

 type of the Family, but is peculiar in every part; it is 

 remarkable from being situated so near the upper (or pos- 

 terior) end of the capitulum, this being caused by the great 



* In the middle, the fold is slightly prominent and pointed, and being most 

 finely villose, I for some time looked at this projection as a rudiment of the 

 probosciformed penis. 



