Bibliographical Notices. 447 



face of the sac or mantle. Here each hecomes invested by a sheath 

 formed by the chitinous epidermis of the sac. A new epiderm being 

 developed on the inner, or under, surface of the sheet of ova, they 

 are detached, adhering only by a small band, — the ' ovigerous 

 fraenum.' As there is no vagina, Mr. Darwin supposes that the ova 

 are fecundated as they pass out, but seems inclined to think that 

 an internal communication between the two sets of organs may also 

 exist. Such a mode of exit appears at first sight anomalous enough, 

 but is not without sufficient analogy. In the Salpce, for instance, 

 the ova, which lie almost free in the blood-sinuses, only attached by 

 a dehcate pedicle, are extruded without any oviduct by passing into a 

 diverticulum of the wall of the sinus which gradually closes behind 

 them ; and there are AnneUds in which exactly the same process 

 takes place. 



We should far exceed our Umits if we were to advert to all the 

 matters of interest in this remarkable book. Those who wish to 

 learn many anatomical novelties — the nature of the nervous system, 

 of the olfactory and auditory organs, &c., must turn to the work 

 itself. We can here only advert to two points, which, like children, 

 we have reserved as boiines bouches for the end. 



In the first place, we could not have held up our head again in the 

 critical chair without finding an error ; and here it is : " Chitine is 

 confined to the Articulata;" though, as it is only contained in a 

 note at p. 30, and is by no means of importance to the general purport 

 of the work, the difficulties of our search may be conceived. Seriously, 

 however, we notice the mistake because it is one which is very gene- 

 rally admitted. The fact is, on the contrary, that Chitine exists in 

 the'jaws and sepiostaire of Cephalopods ; in the lingual plate in these 

 and the Gasteropoda — the jaws of Helix — the shells of CymbuUa, 

 Aplysia and BiiUcBa — the byssus of Lamellibranchs — the shell of 

 Lingula and the skeleton of Gorgonia, — ^besides being present in a 

 number of the annxdoid forms of the Radiata (Leuckart, Wiegm. 

 Arch. 1852). 



The other matter to which we would refer is Mr. Darwin's dis- 

 covery — most important in a physiological point of view — of the 

 existence, in certain species of Ibla and Scalpellutn — true and com- 

 plete hermaphrodites, be it remembered — of what he aptly terms 

 * Complemental Males J 



Mr. Darwin appears to us to produce an overwhelming body of 

 evidence in favour of the conclusions at which he arrives, which are, 

 in a few words, these : — In certain species of these two genera the 

 generality of the larvae become Barnacles, to all appearance as com- 

 pletely provided with all the requisites for the continuation of the 

 species as the other members of the genus, the testes and ovaria 

 being well-developed. A careful eye, however, might discover pits 

 on the scutum or folds upon its edge, of a peculiar character. The 

 fact is, these pits and folds are a sort of arm-chairs for the occupation 

 of a small male, developed from certain other ova, who at an early 

 period of development takes possession of his seat, and attains no 

 further stage. Mouthless and stomachless, ' wholly supported by 



