34 STUDIES IN AMERICAN TETTIGONIIDAE (oRTHOPTERa) 



1900. Engonias-pis Scudder, Proc. Davenp. Acad. Nat. Sci. viii, p. 96. 



(Genus properly characterized.) 

 1900. Slipator Rehn, Trans. Amer. Entom. Soc, xxvii, p. 90. (To replace 



the preoccupied genus Orchesticus Saussure.) 



The genus was based on three species: pachijmerus and dor- 

 salis Burmeister and gihhosus Scudder. 



Genotype: Atlanticus pachymerus [Decticus pachyyneriis] (Bur- 

 meister), selected by Kirby, 1906. 



Generic Position. — The position which was assigned to the 

 genus by Caudell in 1908/ i. e. adjacent to Stipator of authors 

 (vide page 44), appears to us to be the correct one. Without 

 a more detailed study of all the related genera we can not analyze 

 the features of relationship to the. several allied North American 

 and certain Old World genera. The chief feature of difference 

 from Slipator of authors {Pediodectes, vide page 45) is in the 

 possession by Atlanticus of distinct and continuous, though 

 sometimes rounded, lateral marginal angles to the pronotal disk. 



Generic Description. — Head not prominent, of medium size; 

 f astigium moderately prominent, varying from one-third to two- 

 thirds (calcaratus) of the width of the interocular space; eyes 

 subcircular to flattened (cephalad) circular in outline, hardly 

 to distinctly prominent. Pronotum large, much produced 

 caudad over remaining thoracic segments and proximal section 

 of abdomen; disk subdeplanate to well rounded in transverse 

 section, in form slightly to greatly narrowed at or in cephalic 

 third or fourth or narrow and subequal in width, cephahc margin 

 of disk truncate to weakly emarginate, caudal margin subtrun- 

 cate to strongly arcuate; lateral angles of disk always indicated, 

 persistent, gently rounded or prominent and cariniform, median 

 carina absent or indicated caudad; lateral lobes longer than deep, 

 humeral sinus distinctly, weakly or not at all indicated. Pro- 

 sternum with or without distinct spines. Mesosternal lobes 

 angulate produced. Tegmina of male abbreviate, merely strid- 

 ulating organs wholly or largely concealed under the pronotum, 

 strongly vaulted in form, overlapping, with stridulating field 

 well developed. Tegmina of female rudimentary and wholly 

 covered by the pronotum. Wings vestigial. Limbs moderately 

 robust. Cephalic femora with the ventro-cephalic margin 



1 Genera Insectorum, fasc. 72, Decticinae, p. 14, (1908). 



