Bibliographical Notices. 83 



while in some others it is coiled spirally " in the stomach ;" the 

 Tunicata, we are tolcl, have no tongue. Some of the technical terms 

 are used in such a sense as to require a special glossary ; thus (at 

 p. 13 j some opercula are said to be " annular and multispiral," while 

 in other places (e. g. p. 3-45) concentric opercula are called "an- 

 nular." In plain English " annular " means like a ring, i. e. with a 

 hole in the middle, and " no operculum presents an annular form *." 

 At p. 14 we are informed, " the epidermis, like that of other animals, 

 is inorganic, and cast off occasionally by the animal," and the shell 

 itself is called "epithelium." At p. 18 the Octopoda are defined as 

 having "foot none;" but to make up for it, at p. 16, they have 

 "ears developed." This last announcement would have amazed us 

 more, but for the recollection of the phrase " auricular crests " em- 

 ployed by D'Orbigny for the little processes on the sides of the head 

 in some Calamaries, and which have as much to do with hearing 

 as the " ears " of the sea-hare. Under the genus Achatinella it is 

 stated that "the females are ovo- viviparous " (p. 136), and again 

 under Partula, "the females produce their young alive" (p. 145) ; 

 we will not ask what the males are. 



The references to fossil shells are few, and would have been better 

 omitted, as the authors appear to have had no experience in such 

 matters. They are certainly wrong in referring ^larginella pellucida 

 to the extinct genus Voloaria (p. 1 94) ; and are evidently misinformed 

 about Discohelix and Serpidaria, or they would not have described 

 recent shells under those names. 



Not much is made of the geographical distribution of the genera ; 

 at first the notices are very few and loose, but are more frequent 

 afterwards, as the subgenera of land shells were chiefly founded on 

 geographical considerations. We do not know what was intended by 

 " north coast of America " given as a locality of Oleacina ; but at 

 p. 92, for "low latitudes" we should read "high." Tornatellina is 

 said to be found in Madeira, but the only jMadeiran species is removed 

 to another family. 



Most writers, especially when their publications extend over several 

 yeai's, become more cautious as they proceed, and we hope soon to 

 congratulate the authors on the completion of their work in a style 

 improved by experience ; we shall do so more heartily if they will 

 use the opportunity afforded by their preface and appendix to ac- 

 knowledge and correct such things as may yet be rectified. 



Das Gehiss der Schnechen, zur Begrilndung einer natilrUchen Classi- 

 fcation, untersucht von Dr. F. H. Troschel, Professor an der 

 Universitat zu Bonn. Erste Lieferung, mit vier Kupfertafeln voh 

 Hugo Troschel. Berlin, 1856, 4to. 



Dr. Troschel says that he has devoted twenty years to the study of 

 the teeth of Mollusca, and laboured to collect every material that could 

 throw light on the subject. He considers that there are now two 

 classes of students, conchologists and malacozoologists ; the latter take 

 the only imperishable, unchangeable organ of the molluscous animal 

 * Owen, Hunterian Lectures on the Invertebrata, p. 543. 



6* 



