26 CIRJUPEDIA. 



of the outer integument which is not frequently moulted, 

 and, apparently in consequence, the males are attached to 

 its edges. It results from this position, that the males 

 are protected by being enclosed within the cavity ex- 

 cavated by the female ; and it further results, that the 

 males are attached at a considerable distance from the 

 orifice of the sack of the female, into which the sperma- 

 tozoa have to be conveyed ; and to effect this, the pro- 

 bosciformed penis is wonderfully developed, so that in 

 Cryptophialus, when fully extended, it must equal between 

 eight and nine times the entire length of the animal ! 

 These males, like those last mentioned of Scalpelluin, 

 consist of a mere bag, lined by a few muscles, enclosing an 

 eye, and attached at the lower end by the pupal antennae ; 

 it has an orifice at its upper end, and within it there lies 

 coiled up, like a great worm, the probosciformed penis, 

 and beneath it a single testis, with a single vesicula semi- 

 nalis. These organs complete the whole organisation of the 

 male ; for there is no mouth, no stomach, no thorax, no 

 abdomen, and no appendages or limbs of any kind. Yet 

 all these parts are present in the female. 1 know of no 

 other instance in the animal kingdom of such an amount of 

 abortion. The whole exterior of these males evidently 

 is composed, as in all ordinary Cirripedes, of the three first 

 cephalic segments ; of the fourteen succeeding segments of 

 the archetype Cirripede we have not a vestige, excepting 

 the probosciformed penis, which, from analogy, should arise 

 from the ventral apex of the seventeenth segment, the first 

 three segments of the head being counted in the seventeen. 

 Here, then, fourteen out of seventeen segments have aborted, 

 the tip of the seventeenth having coalesced with the third 

 cephalic segment ! I am tempted just to notice the case of 

 Proteolepas, in the order Apoda, as showing, within the 

 limits of the same sub-class, a w 7 onderful amount and diver- 

 sity in abortion ; for in Proteolepas, the three anterior 

 cephalic segments are reduced to the merest rudiment, 

 encasing the cement-ducts, the fourteen succeeding segments 

 being unusually well developed ; whereas in the above des- 

 cribed males, we have just seen the three anterior segments 

 fully developed, whilst the fourteen succeeding segments 



