1852.] 



41 



these species were referred by me to the genus Pachylopus (vide Ann. Lye. 

 Nat. Hist. 5.) The epipleurae of these last are marked with three striae. 

 The spines on the tibiae of S. dimidiatipennis are less numeroas than in the 

 others, and form four tolerably distinct series. 



Synopsis of the ParniDjE of the United States. 



By John L. Le Conte, M. D. 



As I have concluded, for reasons detailed below, to introduce the anomalous 

 genus Eurypalpus into this family, I have found it necessary to substitute an en- 

 tirely new diagnosis for the one given by Erichson. The one proposed by me, 

 in order to include the new genus, is as follows: 



AjitetincB frontales, no7i capitatce ; oculi rotundati, mandibidce retractce ; coxce 

 anticcB vel sitbcylindriccB, vel globosce. acetabulis e prostenio et metathoracis epi- 

 sternis compositis receptee ; pedes ambulatorii^ tarsi 5-articiilati ^ cyliiidriciy 

 unguicidari ornaximCjUnguihus validis armato ; trochanteres simplices ; abdomeii 

 5 l-articulatuviy articulis anteiiorib%Ls immobilibus. 



The character which especially distinguishes this family is the structure of the 

 tarsi, which enables the species to grasp firmly objects resting in strong currents 

 of water. This family may be divided into three groups. 



Div. 1, Ezcrypalpini, 



Caput exsertum, ore inferno, labro distincto, inter antennas transverse eleva- 

 tum ; coxae anficas transversae, trochantino valde conspicuo; parapleurae appen- 

 diculatae ; abdomen 7-articulatum. 



EuRYrALPusj Dej. 



Antennae serratae 11-articulatae ; palpi maxillares valde elongati, articulo ulti- 

 mo latiore, securiformi, apice subacuto ; labiales brevissimi, articulo ultimo 

 minuto subulato. 



This very remarkable genus is mentioned by name in Dejean's Catalogue, and 

 is placed by that author towards the beginning of bis group Malacodermata, near 

 Cyphon, with which, however, it seems to have but little affinity. Erichson, 

 probably never having seen the insect, referred it upon Dejean's authority, to 

 Cyphones, with a doubt. (Vide Agassiz Nom. Zool.) A close comparison with 

 other groups has convinced me, that although its affinities in any direction are 

 difficult to discover, it must still be considered as forming a part of the present 

 family. 



The body is depressed, narrowed in front, obtusely rounded behind. The 

 mandibles are small, acute and entirel)'' concealed by the broad and emarginate 

 labrum ; the mentum is trapezoidal ; the ligula short, square and slightly emar- 

 ginate at tip. The prosternum is truncate in front, prolonged behind into an 

 acute point which passes in a narrow groove extending the whole length of the 

 mesosternum. The anterior coxae are precisely as in Helichus ; the posterior 

 coxae are slightly laminate and dilated interiorly as in Helichus, but are conti- 

 guous at their base ; the parapleurse are broadly truncate at the external posterior 

 angle, and the parallelogram is completed by a large triangular plate. The ab- 

 domen is 7-jointed, the first three joints are immovable, the 5th deeply emar- 

 ginate, the 6th retracted so as to have only the edge visible, the last joint almost 

 round; the feet have the last joint much longer than the other four united, with 

 strong simple claws. 



The larva resembles in appearance a Trilobite, and has been described by 

 De Kay as a Crustaceous animal under the name Fluvicola Herricki. It is en- 

 tirely aquatic, and breathes by means of branchial filaments, the principal ot 

 which proceed from the anus. For a full description o{ it and the pupa see 

 Agassiz' Lake Superior. It bears a close comparison with the larva of Elmis by 

 Erichson, (Deutschl. Insect. 525). 



6 



