ALC1PPE LAMPAS. 545 



that I have correctly named the different parts ; and a few 

 remarks on this head may be desirable, considering the 

 absence of certain cirri, the singular condition of the others, 

 the close general resemblance of the cirri and caudal ap- 

 pendages, and the fact of the latter being furnished with 

 muscles. The only cause for any doubt regarding the thoracic 

 segments is the shield of thick membrane on that segment 

 {k, fig. 5), which ought to have borne the second pair of 

 cirri, causing two transverse wrinkles (not distinguishable, 

 however, on the ventral surface), and sometimes making 

 the segment appear as if it consisted of three segments : 

 if it did consist of three, as there can be no doubt about 

 the nature of the first pair of cirri, (not in a more rudi- 

 mentary condition than in Anelasma) or about the seg- 

 ment whence this first pair arises, the two terminal oblique 

 segments, with their appendages, would be abdominal in- 

 stead of thoracic : but this is improbable, inasmuch as the 

 abdomen is unusually little developed in the pupa (as 

 presently to be shown), and more especially from the cir- 

 cumstance of a monstrous cirrus, identical in structure with 

 the two succeeding pairs, having been borne on a segment 

 (m), which, in any case must be considered as thoracic, for 

 it is well known how very rarely thoracic and abdominal 

 limbs resemble each other. I cannot myself feel hardly any 

 doubt on the nature of these three pairs of appendages ; 

 for, in the first place, the posterior appendages are articu- 

 lated on and between the bases of the adjoining pair, ex- 

 actly as the undoubted caudal appendages are articulated 

 in all other members of the family on the sixth pair of cirri 

 or terminal thoracic appendages. Secondly, we see in the 

 male of the allied genus Ibla, the very same appendages 

 preserved as in Alcippe, namely, the caudal, and the fifth 

 and sixth pairs of cirri, which latter, moreover, are generally 

 uniramous. Thirdly and lastly, in the likewise allied Alepas 

 cornuta, we have the posterior rami of these same fifth and 

 sixth pairs of cirri in a rudimentary condition, and re- 

 sembling in every respect the caudal appendages. Assuming, 

 then, that the several appendages in Alcippe have been 

 rightly denominated, we have to consider the nature of 

 their segments : in all cirripedes, the pedicels of the cirri 



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