ALCIPPE LAMPAS. 543 



ferent appearance according to the point of view, fig. 9, 10 : 

 on one of its sides it projects beyond the outline of the 

 second segment, whence it arises ; on the other side it is 

 prolonged, as a smooth ridge, on the top of the second 

 segment, embracing to a certain extent the base of the 

 third segment. On the face opposite to that which has 

 been drawn (fig. 9) as most characteristic, it is seen to be 

 somewhat constricted round its base ; this constriction, re- 

 presenting, I believe, an articulation. When viewed directly 

 in front (fig. 10) its outline is oval, passing into shield- 

 shaped. Its longitudinal axis is ^ths of an inch in length ; 

 but it varies a little in shape and size. I shall presently 

 assign my reasons for believing that these buttons are the 

 posterior or inner rami of the fifth and sixth pairs of cirri 

 in a rudimentary and much modified condition. 



Caudal Appendages. — These (fig. 13,j») are placed close to- 

 gether, being articulated between the bases of the sixth pair 

 of cirri, the lines of junction being internally marked by 

 minute apodemes. They consist of four segments, re- 

 sembling in every respect those forming the cirri, with the 

 important exception that there is not a vestige of the 

 button on the summit of the second segment ; the segments 

 are not so thick as those of the cirri, and the terminal seg- 

 ment is smaller. 



Muscles and Functions of the Cirri. — For their size, the 

 cirri and caudal appendages have voluntary muscles of 

 remarkable strength, attached within their basal segments, 

 and springing from the dorsal and ventral surfaces of the 

 so-called third and fourth (I, m) thoracic segments. Other 

 muscles, rising from within the basal segment of each limb, 

 run to the second segment, and -from that to the third seg- 

 ment. I could not distinctly make out whether any entered 

 the terminal segment. I have seen no other instance of 

 muscles entering the caudal appendages, but as in the pupa 

 they are so furnished, we here have only an embryonic cha- 

 racter preserved. I may remark that the fifth and sixth 

 cirri, consisting of two large basal and two thinner terminal 

 segments, is likewise an embryonic character. From the 

 position of the cirri, the four hard protuberant buttons or 

 cushions, tend to oppose each other at a common point ; 



