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 outline, 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 super ius 

 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 

 inequivalve; 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 quce adservan-* 

 tur in MUSCEO Nicolai Gualtieri, Philosophi et Medici, Flo- 

 renting 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 

 important character, and one of easy application, having oh- 



