Bibliographical Notices. 
459 
Silurian. 
C. striatella. 
— cornuta. 
Devonian. 
C. Falklandica. 
— sarciniilata. 
— dilatata. 
— crenulata. 
— liana. 
— setigera. 
— arrnata. 
— ininuta. 
— convoliita. 
Carboniferous. Permian. 
C. concentrica. C. variolata?? 
— papilionacea. 
— comoides. 
— Shuniardiana. 
— Dalmaniana. 
— sulcata. 
— Buchiana. 
— tuberculata. 
— variolata. 
— elegans. 
— Laguessiaiia, 
— perlata. 
From the inspection of the above table, it appears that the genus 
Chonetes attained its greatest development in the carboniferous 
system ; it is there also that the species present many varieties of 
form and are of the greatest size. This latter remark applies also 
to Productus, to which Chonetes is closely allied. However, the pro- 
portion in which this development has taken place is very different 
for the two genera. With regard to their distribution in time, the 
following conclusions are drawn from the table above quoted : the 
two Silurian species belong to the upper beds of the system ; in the 
Devonian system the C. Falklandica, sarchiulata and dilatata cha- 
racterize the inferior beds, the C. crenulata, nana and setigera are 
characteristic of the middle portion, and the G. arrnata, minuta and 
convoluta are found only in the upper beds of the same system. The 
C. concentrica, papilionacea, comoides, Shumardiana, Dalmaniana, sul- 
cata, Buchiana and tuberculata belong exclusively to the inferior 
beds of the carboniferous system, the C. elegans to the middle, and 
the C. Laguessiana and perlata to the superior beds of the same 
system ; and lastly, the C. variolata belongs to different carboniferous 
deposits, and appears even to pass into the Permian system. 
In a memoir of this nature, it is almost impossible to attain abso- 
lute correctness, more especially from the author not having had the 
means of verifying all the species from original or well- authenticated 
specimens ; independently, however, it is a work of great research, 
and will be of considerable value to the palaeontologist, in placing 
before him carefully executed figures of the species belonging to 
these two genera. The volume is in quarto, illustrated by 20 plates, 
and contains also an alphabetical, synonymical and chronological 
table of all the species. 
Monographia Heliceorum Viventium, sistens Descriptiones systematicas 
et criticas omnium hujus families generum et specierum hodie cogni- 
tarum. Auctore Ludovico Pfeiffer, Dr. Cassellana. Fasc. 1,2,3. 
Lipsiae, 1847-48. 
It is with great pleasure we announce the appearance of the com- 
pletion of the first volume of this excellent monograph, containing 
