502 



B i b ii og r a pin c al Notice % . 



detected on the under than on the upper surface, especially in those 

 Gasteropods (Limax, Helix) whose pairs of ganglions of the lower 

 portion of nerves are more confluent {verschmolzen). They have been 

 found on all species hitherto examined, as Helix pomatia, arbustorum, 

 nemoratis, hortensis, rotundata and hispida, Succinea amphibia, Lym- 

 nceus stagnalis and minutus, Physa fontinalis, Planorbis marginal us, 

 vortex, nitidus and contortus, Clausilia plicata, nervosa and minima, 

 Ancylus jluviatilis, Bulimus lubricus, Limax agrestis and maximus, and 

 Arion empiricorum. The organs of hearing are always present in 

 pairs, and are formed of two capsules having transparent walls. 

 These capsules may even be detected with the naked eye in the 

 larger species on pressing the ganglion of the brain between plates 

 of glass. Both capsules are situated on the posterior vaulting of the 

 anterior pair of ganglia of the lower central portion of nerves so 

 closely, that where they join the ganglionic mass it is difficult to de- 

 tect the limits between the ganglion and the wall of the capsule, espe- 

 cially as they nearly agree in colour. In the cavities of these two 

 capsules are inclosed an immense number of transparent crystalline 

 bodies, consisting of carbonate of lime. The form of these otolithes, 

 for as such they must be considered, is oval and flat, their borders 

 seem to be gently rounded off. They oscillate so lively in the capsules 

 as almost to lead to the belief they were jerked one among the other 

 by a vibrating ciliatile epithelium clothing the inner wall of the cap- 

 sule, but never could a trace of cilia be detected. In a note the 

 author expresses his belief that the Annelides are also furnished with 

 similar organs of hearing, judging from the description which Stan- 

 nius has given in his anatomy of Arenicola piscatorum of bodies re- 

 sembling otolithes, which likewise occur in closed capsules. 



On the Balanidea, by Prof. W. v. Rapp, p. 168—174. The shells 

 of the non-petiolated Cirrhipoda {Balanidea) differ from the shells of 

 Mollusca and of the petiolated Cirrhipoda (Lepadea) by their pecu- 

 liar internal structure. The genera Balanus, Coronula, Tubicinella 

 all agree in this respect, viz. in their shells being perforated by re- 

 gular canals. The structure of these canals, as well as of the animal, 

 is described at length in Tubicinella balcenarum, Coronula diadema, C. 

 baltenaris, Balanus spinosus, and other species of this last genus. 

 Speaking of the young of Tubicinella balanarum, the author observes 

 that he found here what Thompson and Burmeister had shown to 

 exist in other Cirripedes, a form totally differing from that of the 

 adult ; he could detect no eyes, nor a trace of shell. It is not to be 

 admitted that the Tubicinella derives its nutriment from the whale, 

 but most probably from the flocks of Cyamus, with which the bodies 

 of the latter are infested. The animal of the non-petiolated Cirrhi- 

 poda differs essentially from those of the petiolated by the branchiae ; 

 these organs are narrow pointed lamina? in the Lepadea, while in the 

 Balanidea a large branchia is situated on each side of the animal, 

 formed of a membrane folded in nearly regular laminae, as already 

 observed by Cuvier and Hunter.* W. Francis. 



* Want of space compels us to leave the remainder over for next month. 

 —Ed. 



