23 MOLLUSCA. 
afterwards so successfully and admirably seized by the great 
reformer of natural history in general.” But Langius de- 
serves more praise than is here bestowed upon him. Be- 
fore his system appeared, the characters of the genera de- 
pended principally on the owt/ine, and were of uncertain ap- 
plication. He remedied the defect, by directing the atten- 
tion of conchologists to the form of the mouth in univalves, 
and to the structure of the hinge in bivalves. Among the 
former, he constituted subdivisions of those ore superius 
aperto, ore superius in canaliculum abeunte, and ore su- 
perius clauso. Amongst the latter, the circumstance did not 
escape him, that some of these shells are. eguivalve, others 
mnequivalve ; some equilateral, others inequilateral. Hence 
he may be considered as the founder of the inferior divi- 
sions of the artificial method, and as having furnished, to 
modern conchologists, many useful hints, of which they have 
availed themselves, without, however, acknowledging their 
origin. 
Another important improvement was effected by Brey- 
nius in his Dissertatio Physica de Polythalamiis, 1732, in 
4to. This consisted in separating from the ordinary uni- 
valves, such shells as possess a cavity divided by partitions 
into several compartments, and in forming them into a di- 
vision, which he termed Polythalamium. These shells are 
now called Multilocular. 
The system of Tournefort, which was published by Gu- 
altieri, in his Index Testarum Conchyliorum que adservan- 
tur tx» Museo Nicolai Gualtiert, Philosophi et Medici, Flo- 
xentint, 1742, well deserves an attentive perusal. In his 
observations on the bivalves, now denominated the acephal- 
ous mollusca, he drew the attention of conchologists to an 
impertant character, and. one of easy application, having ob- 
