THE CRUSTACEA 



which are lodged quite inside the pallial cavity, on the dorsal side 

 of the body. Of the two species composing the 

 genus Ibla, one, /. qnadrivalvis, has hermaphrodite 

 individuals (Fig. 71) with complemental males, 

 while the other, /. cumingii, has the sexes separate. 

 The males of the Acrothoracica (Fig. 72) are 

 still further modified. The appendages and ali- 

 mentary canal are quite wanting and the mantle 

 forms merely a sheath for the greatly developed 

 penis, which, in Alcippe, can extend to three or 

 four times the length of the body. These an- 

 enterous males must of necessity be short-lived, 

 and in addition to the two to fourteen males which 

 are attached to the mantle margin of a single 

 female, there will often be found the remains of 

 FIG. 71. the adhering antennules of several others which 



'nia qwuiriwtivis. have attached themselves and died since the last 



(From Gruvel's 



Monographic.) moult of the female. 



There can be but little doubt that herma- 

 phroditism is the primitive condition among the Cirripedia, though 



Dwarf male of Alcippe lampas. An, antennules ; C.def, vas deferens ; C.p, canal of the penis 

 (vestige of mantle-cavity) ; (? lt G 2 , nerve-ganglia ; mus, retractor muscles of the penis ; p, 

 penis ; pi, pigment ; Tes, testis ; t.c, connective tissue ; V.s, seminal vesicle. (After Berndt, 

 from Gravel's Monographic.) 



