398 CLASSIFICATION OF THE CARABID.E 



X. Carabi, (genuini.) 



A group containing insects of varied form, usually of large size, and having in common 

 nearly filiform anterior tibia?, which are not emarginate internally, and which have the 

 usual spurs both placed at the apex : the most remarkable character distinguishing them 

 is the imperfection of the anterior acetabula, the posterior margin of which is membranous, 

 so that the coxa comes in contact with the mesosternum. The prosternum is more or 

 less produced behind; the mesosternum is declivious and carinate anteriorly, and concave 

 posteriorly. The anterior tarsi of the males, when dilated, are spongy beneath: many of 

 the species are remarkable for possessing a greater number of elytral striae than is found 

 in any of the preceding groups. 



Our native genera are Cychrus (including Scaphinotus and Sphreroderus,) Carabus, 

 Callisthenes, Calosoma, Nebria, Notiophilus and Opisthius, besides a new genus allied to 

 Cychrus, below described.* 



Of Cychrus, there are in my collection eighteen species, which may be thus classified: 



A. Thorax plus minusve cortlatus, (tarsi maris paruin diktat!.) 



a. Thorax valde marginatus. 



1. Margine thoracis laterali postice valde dilatato : C. u n i c o 1 o r Oliv.; elevatus Fair.; d i 1 a- 

 t a t u s Lee. {Scaphinotus flam.%Lec.) Scaphinotus lieros Harris (Bost. Journ. Nat. Hist. 2, 196) 

 belongs to this group: I formerly considered it as identical with C. un i col or, but on comparing 

 the original specimen in the collection of the Academy of Natural Sciences, I find that it differs in 

 having much more convex elytra, being in appearance intermediate between C. unicolor and viduus. 



2. Margine thoracis postice vix latiore : C. viduus Dej. and A n d r e w s i i Harris. C. Leon- 

 ardi Harris, is a variety of the first mentioned. 



b. Thorax anguste mai'ginatus. 



3. Elytra striata: C. an gus tic o His Fischer; marginatus Dej.; ventricosus Dej. 

 Fsch. (striatopunctatus Chaud. ;) inter ruptus Men. [ventricosus % Chaud. ;) const rictus Lee. 

 and cordatusicc; also C. angulatus Harris; cristatus Harris, and vclutinus Men., which are 

 unknown to me. 



4. Elytra tuberculata : C. tuberculatus Harris. 



B. Thorax fere rotundatus, tenuiter marginatus (tarsi maris valde dilatati.) 



5. C. stenostomus Weber; C. nitidi colli s; n i aga re n s i s; Lecontei; Bre- 

 v o o r t i Lee. and a new species C. bicarinatus. The second species was first described by 

 Guerin, the third by Laportc, the fourth by Dejean, and the fifth by myself as Sphseroderus. 



As a fact in geographical distribution, it may be stated that the species in (B) and (a) 

 are confined to Atlantic North America; those in (b) are only found on the Pacific slope 

 of the continent. 



The new species, above mentioned, may be distinguished as follows: 



C. c on str ictus, ater, thorace subopaco, valde cordato, lateribus maxime rotundatis, postice sinua- 

 tis, angulis posticis rectis, non prominulis ; clytris ventricosis, crcnatostriatis, apice acuminatis, inter- 

 stitiis vix interruptis. Long. '0. 



* Pelophila ami Leistus arc seiid lo occur in Western North America, but the species are unknown to me. 



