SEXUAL RELATIONS. 23 



On the Sexual Relation of Cirripedes. 



Cirripedes are commonly bisexual or hermaphrodite, but 

 in Ibla, Scalpellum, and Alcippe, members of the Lepaclidse 

 in the order Thoracica, and in Cryptophialus in the order 

 Abdominalia, the sexes are separate. As two of these 

 genera were described in my former volume, and two others 

 (Alcippe and Cryptophialus) are described in this volume, I 

 may as well here give a brief summary of the facts as yet 

 known on this very curious subject. The Males, in the 

 above four genera, present a wonderful range of structure ; 

 they are attached in the usual way by cement proceeding 

 from the not-moulted antennae of the pupa, to different 

 parts, in the different species, of the female. These males are 

 minute, often exceedingly minute, and consequently gene- 

 rally more than one is attached to a single female ; and I 

 have seen as many as fourteen adhering on one female ! 

 In several species the males are short-lived, for they 

 cannot feed, being destitute of a mouth and stomach. As 

 the females are longer lived, successive crops of males, at 

 each period of propagation, become attached to her. It is 

 the females in the above genera which retain the characters 

 of the genus, family, and order to which they belong ; the 

 males often departing widely from the normal type. Some 

 of the males are rudimentary to a degree, which I believe 

 can hardly be equalled in the whole animal kingdom ; they 

 may, in fact, be said to exist as mere bags of spermatozoa. 

 So widely do some of them depart in every character from 

 their class, that twice it has happened to me to examine 

 specimens with a little care, and not even to suspect, until a 

 long period afterwards, that these males were Cirripedes.* 



* In my volume on the Lepadidse (p. 200) in searching for analogies for the 

 permanently epizoic and rudimentary condition of the male Cirripedes, I quoted 

 two cases, which I believe are now known not to be analogous ; namely, the 

 Spigamus trachealis of Von Siebold, and the worm-like Hectocotyle, which latter 

 was quite lately supposed to be a male Cephalopod, but has now been ascer- 

 tained to be only one of the arms of the male wonderfully adapted and organised 

 as a sperm-receptacle. The Asplanchna, the mouthless male of a Rotifer, 

 (p. 292) alone remains for me. 



