1854.] 41 



g. Pedes testacei, vel run; thorax convexus tenuiter mar- 

 ginatus. Sp. "" 33. 



E. Corpus alatum, gracile; thorax ovalis, vel leviter cordatus, tenuius mar- 

 ginatus ; elytra tripunctata; pedes plus minusve testacei. Sp. 3440. 



F. Corpus alatum, gracile, praecipue elongatum; thorax ovalis ; elytra multi- 

 punctata; pedes plus minusve testacei. Sp. 41 48. 



G. Corpus alatum; thorax rotundatus, tenuissime marginatus ; 

 elytra foveata. Sp. 49. 



H. Corpus alatum, minus gracile, thorax praecipue rotundatus (praecipue 

 tenuiter marginatus) impressionibus basalibus latis, minus profundis ; elytra 

 multipunctata. 



h. Corpus elongatum metallicum, pedes concolores. Sp. 50 51. 



i. Corpus minus elongatum sub^racile, pedes plus minusve testacei. 



Sp. 5254. 

 k. Corpus robustius, angulis thoracis posticis fere distinctis. Sp. 55 56. 

 I. Corpus alatum, fere gracile, elytra oblonga, basi valde emarginata, apice 

 fere truncata; elytra vel tripunctata, vel quadrifoveata. Sp. 57 61. 



The cases of difficulty, in referring species by this table, will be but few ; a 

 species (P. quadratus) is placed in (f.,) which might, with almost equal propriety, 

 be placed with (d.) ; still, the form is less slender, and the margin of the thorax 

 much more obvious than in the latter group. 



P. crenulatus in group (F.) differs from the others of the same group, by the 

 broader and more quadrate elytra ; still, its chief affinities appear to be with that 

 group, and I have, therefore, not separated it from its allies. 



A. 



The species of this group are of a slender form and not winged ; the legs and 

 antennae are long ; the thorax is obovate, usually elongate ; the posterior angles 

 are obtuse and rounded at the apex ; the lateral margin is strongly reflexed, and 

 is broader than usual. The elytra are regularly elliptical, with no distinct hu- 

 meral angles ; they are sinuate towards the tip ; the lateral margin is broader 

 than in any other group, and is strongly reflexed. This group corresponds to 

 Platynus of Bonelli and Dejean. 



1. P. f ra g il i s, piceus,thorace latitudine fere longiore obovato, fortius mar- 

 ginato, angulis posticis obtusis, subrotundatis, basi transversim profunde im- 

 presso, elytris ellipticis, thorace duplo latioribus, fortius marginatis, tenuiter 

 striatis, 3-punctatis, antennis versus apicem subincrassatis. Long. -34. 



Found in the mountains near Santa Isabpl, in the southern part of California. 

 One specimen has four impressed punctures on the elytra. The antennae, instead 

 of being setaceous, as in the next two species, are slightly thickened beyond the 

 fourth joint, as in most of the species of this genus. 



2. P. h y p o 1 i t h o s, niger nitidus, thorace latitudine fere longiore, obovato, 

 fortiter marginato, angulis posticis obtusis rotundatis, basi transversim profunde 

 impresso, utrinque longius sat profunde impresso, elytris thorace duplo latioribus 

 ellipticis fortius marginatis, striis modice profundis, interstitiis convexis 2, 4 et 

 6to juxta striis biseriatim irregulariter punctatis, antennis setaceis palpis pedi- 

 busque ferrugineis. Long. 55. 



Feronia hypolithos Say, Trans. Am. Phil. Soc. 2, 59. 



Platynus erythropus Dej. Sp. Gen. 3, 97. 



Middle and Western States, in the vicinity of mountains. Besides the punc- 

 tures mentioned, there are several on the sutural stria before the middle. De- 

 jean's description is very full, but lest any entomologist should hesitate in refer- 

 ring this species to the description given by Say, which is certainly defective in 

 some particulars, I transcribe it to save the labor of future reference. 



"Apterous, black, glabrous : feet rufous ; striae of the elytra punctured. Length 

 more than ll-20th of an inch. 



"Antennae dark piceous ; palpi rufo-piceous. Thorax narrowed behind, dorsal 



