16 FOSSIL CIRRIPEDIA. 



with straight spines, serving, apparently, to protect the entrance of the sack : the whole 

 aninial is attached, like ordinary cirripedes, first by the prehensile antennse, and afterwards 

 by the cementing substance ; the whole animal may be said to consist of one great 

 sperm-receptacle, charged with spermatazoa ; as soon as these are discharged, the animal 

 dies. 



A far more singular fact remains to be told : ScaJpeUum vultjare is hke ordinary cirripedes, 

 hermaphrodite, but the male organs are somewhat less developed than is usual ; and, as 

 if in compensation, several short-lived males are almost invariably attached on the occlu- 

 dent margin of both Scuta, at a spot marked by a fold (not thus caused), as may be seen 

 on the inside view of this valve in the fossil S. magnum, which, in all probability, was 

 furnished with them. I have called these beings complemental males, to signify that they 

 are complemental to an hermaphrodite, and that they do not pair like ordinary males with 

 simple females. In Scaljjellum vulgare, the complemental male presents only slight specific 

 difierences from the male of S. ornatmn. It would be foreign to the purpose of this 

 volume here to enter on further details ; nor should I have touched on the subject, had I 

 not wished specially to call attention to the presence of cavities on the under sides of the 

 Scuta above the pits for the adductor muscle. I will only add, that in the other species of 

 Scalpellum, the complemental males are more highly organised, and are furnished with a 

 mouth and prehensile cirri ; the valves are more or less rudimental in the different species ; 

 these complemental males are not always present, and are never attached to young herma- 

 phrodites ; when present, they adhere in such a position, that they can discharge their sper- 

 matozoa into the sack of the hermaphrodite : their attachment does not afiect the form of 

 the valves.^ 



Description of Valves. — It will, I think, be most convenient to confine the following 

 description to the fossil species of the genus. No one specimen has been found quite 

 perfect ; but, judging from analogy, the capitulum was probably formed of fourteen valves 

 in 8. magnum, and of twelve in the remaining species. These valves are commonly smooth, 



1 Exactly analogous facts are presented, tliongh more conspicuously, by the two species of the genus 

 Ibla. Before examining this genus, I had noticed the complemental males ou ScaJpellum vulgare, but had 

 not imagined even that they were Cirripedia. Ihla Cuiningli (as I propose to call a new species collected by 

 Mr. Cuming, at the Philippines) is bisexual ; one or two males being parasitic near the bottom of the 

 sack of the female. These males are small, are supported on a long peduncle, but are not enclosed in a 

 capitulum (such protection being here unnecessary), are furnished with a mouth, ordinary trophi, stomach, 

 and anus ; there are only two pair of cirri, and these are distorted, useless and rudimentary ; the whole 

 thorax is extremely small ; there is no penis, but a mere orifice beneath the anus for the emission of semen : 

 hence Ibla Cumingii is exactly analogous to Scalpellum ornatmn. On the other hand, the closely allied 

 Australian Ihla Cuvierii, like Scalpellum vulgare, is hermaphrodite, but has, in every specimen opened by 

 me, a complemental male attached to near the bottom of the sack ; this complemental male diflfers only 

 about as much from the male of Ihla Cumingii, as the female /. Cumingii differs from the hermaphrodite form 

 of I. Cuvierii. I intend hereafter to give detailed anatomical descriptions and drawings of the males and 

 complemenial males of Ibla and Scalpellum. 



