REVIEW. 



Natural History of the British Diatomacece. By Arthur 

 Scott Donkin. M.D. Part III. Van Voorst. 



After an interval of two years the second part of the 

 'Natural History of the British Diatomacese,' by Arthur 

 Scott Donkin, M.D., has been followed by the third, the 

 letter-press in all respects such as might be expected from 

 the publisher. Van Voorst, and the plates, although not 

 equal to those the readers of the ' Quarterly Journal of Micro- 

 scopical Science ' were accustomed to from the exquisite 

 pencil of the late Dr. Greville, are still fairly executed. 



A great deal of useless and confusing nomenclature has 

 been advantageously discarded by the author, as an exempli- 

 fication of which the synonymy of N. limosa may be referred 

 to. Some few matters there are which require special notice. 

 Stauroneis pulchella has been removed from the genus 

 Stauroneis, and placed under the genus Navicula, under the 

 name of Navicula aspera. 



This raises the question whether the genus Stauroneis 

 might not be altogether abandoned. The characteristic is 

 the lateral expansion of the central nodule, so as to form 

 what has been designated a stauros. There is no species in 

 which this character is more marked than in that under con- 

 sideration ; and if this, notwithstanding, be removed to the 

 genus Navicula, there seems no valid reason why the other 

 species of the old genus Stauro7ieis should not be similarly 

 treated. Following Kabenhorst, Dr. Donkin has identified 

 Pinnularia Johnsonii, W. Sm., with Navicula scopulorum, 

 Breb., and N. mesotyla, Ehr. The two latter, judging from 

 the figures, are probably identical, but if Rabenhorst's de- 

 scription of the former be correct, " gegen die gerundeten 

 enden Verlaufend," it can scarcely be regarded as identical 

 with P. Johnsonii, the ends of which are expanded, as accu- 

 rately described in the figures of Smith and Donkin. 



Amphiprora constricta, Ehr., has been removed from the 

 genus to which it has hitherto been assigned, and included 

 in the genus Navicula, under the name of Navicula simulans. 

 Smith's description represents this form as more symmetrical 

 than it is in reality. The characters of the genus Am^hi' 



