530 PROCEEDINGS OF THE NATfONAL MUSEUM. vol. xxxvi. 



notiim. The postscutellum (P.V) laying behind them is alwa3's i\ 

 plate more or less distinctly separated from the notum, but connected 

 or continuously fused with the epimera. 



In the Coleoptera there occur two special modifications of the meta- 

 thoracic tergum which set the beetles apart in this respect from all 

 the other orders. One of these characters is the forward extension of 

 a median tongue of the scutellum toward the prescutum, cutting the 

 scutum into separated lateral halves. The second character is the 

 division of each lateral scutal plate again into two by lines formed 

 by special transverse ventral ridges laterad of the apex of the V-ridge. 



In a separate paper (1909) the author has shown that Audouin's 

 interpretation of the coleopteran tergum is untenable, that, in order to 

 make out his four transverse tergal sclerites, Audoiiin has represented 

 certain parts as continuous which in nature are separate, and in other 

 cases has made separations where none occur. 



A Carabid, Calo^oina scrutator (132, 133), presents a very simple 

 arrangement of the metatergal subdivisions characteristic of the 

 beetles. The prescutum {psc) consists of a large quadrate median 

 part and of two narrow lateral arms widened terminally into the 

 triangular anterior notal Aving processes {ANP). The median part is 

 separated by a membranous area {ml), the '' toile " of Straus-Diirck- 

 heim (1828), from the anterior extension of the scutellum on the floor 

 of the median notal groove {O). On its anterior ventral edge the 

 prescutum carries the prephragma {Aph) mesially and the cup-shaped 

 muscle apodemes {MD) laterally. The scutum (.sc/", set) is divided 

 into four plates b}" the median approximation of the prescutum and 

 scutellum, and by the lines (132, to) formed by the special transverse 

 ventral ridges (133, w). The posterior division on each side carries 

 the posterior notal wing process {P X P). The scutellum (132, scl) 

 presents a median enlargement carrying the tongue extending for- 

 ward on the floor of the median notal groove {G) and determined by 

 the entodorsum or ventral V-shaped ridge (133, F), while laterally 

 it extends to the bases of the axillary cords (.1 x C) as a narrow 

 marginal postscutal strip on each side, determined by the posterior 

 notal ridge {P N R). 



Behind the notum, and entirely separated from it by a flexible 

 suture, is the pseudonotum (postscutellum) {PN)^ carrying the post- 

 jjliragma {Pph) and articulating at its extremities (/) with the 

 epimera. 



Di/tiscus dauricus (13(5, 137), is verj^ similar in its metatergal struc- 

 ture to Calosoma (132, 133). The lateral arms of the scutellum, how- 

 ever, are larger and, in addition to carrying the axillary cards, they 

 support the combined bases (r) of the anal veins of the wing. The 

 ventral ridges (137, T", w) are much larger than in Calosoma. 



