562 LEPADID^E. 



attached, and from the extraordinary length of the probos- 

 ciformed penis, capable of voluntary movements, I have no 

 doubt the males can insert the tip of this organ within the 

 lower edge of the orifice of the sack, and there discharge 

 the spermatozoa, which, by their own movements, must 

 pass down the sides of the sack of female till they reach 

 their proper destination. The position of the males, with 

 respect to the female's body, is almost exactly the same as 

 that occupied by the complemental males of Scedpellum 

 Peronii and villosum; the lower and narrow end of the fis- 

 sure, worn in the gasteropod shell, here affording that protec- 

 tion to the males, which the edges of the opposed scuta afford 

 to the complemental males of the above two species of Scal- 

 pelluin. We cannot doubt that these latter males aid in the 

 impregnation of the ova of the hermaphrodites, but they are 

 not furnished with a very long penis, probably for the very 

 reason that they are complemented males, and therefore not 

 so absolutely necessary for the impregnation of the ova as 

 are the males of Alcippe. 



I have, in my former volume, expressed my astonishment 

 at the extent to which abortion had been carried in the 

 male Ibla; but it has been carried much further in the 

 male Alcippe. In Ibla, the thorax is reduced to a mere 

 flap, and only two pair of cirri exist in a most useless and 

 rudimentary state, but there is a well organised mouth, 

 stomach, and anus. In the males of Scalpelhtm vulgare, 

 orneitum, and rutilum there is no mouth or stomach, but there 

 is a thorax with four pair of minute, modified cirri, and a 

 large abdominal lobe. Here, in the male Alcippe, all these 

 negatives are united, we have no mouth, no stomach, no 

 thorax, no cirri, no abdomen ! The archetype crustacean 

 consists of twenty-one segments; of these the seventeen 

 anterior segments can be clearly made out in the arche- 

 type Cirripede : now, in the male Alcippe, the first three 

 segments are largely developed, forming all that is exter- 

 nally visible, but the remaining fourteen segments are 

 absolutely aborted, but in idea may be considered as form- 

 ing the membranous depression whence the probosciformed 

 penis springs ; for this organ normally arises at the extre- 

 mity of the seventeenth segment. To show the wonderful 



