On Aquatic Carnivorous Coleoi^tera or DytiscidcE. 503 



The shining surface and large meshes of the reticulation are very characteristic ; 

 when a careful examination is made, it is seen that in the middle of these meshes 

 (not on the lines thereof as in most other species), there are excessively minute 

 punctures. 



Colymbetes nitidus, Say. (Tr. Am. Phil. Soc. II. p. 98) is referred to this species 

 on the authority of Crotch. 



North America, (Massachusetts). 788. 



686. Agabusplanatus,n.sp. — Fern. Ovalis,haud convexus, pernitidus, nigro-piceus, 

 colore subtus paulo dilutiore, antennis pedibusque rufis, elytiis pone medium versus 

 latera lineola, et ante apicem gutta testaceis ; supra undique conspicue reticulatus, 

 reticulis magnis ; jjrothorace margine laterali crasso. Long. 9, lat. 5 m.m. 



I have seen but a single individual (?) of this species, which seems to be very 

 closely allied to Agabus obtusatus, but is a good deal larger, and has a much broader 

 lateral margin to the pronotum. 



This is perhaps the insect considered by Ci'otch (Tr. Am. Ent Soc, 1873. p. 417), 

 to be a female variety of Agabus semivittatus, Lee. 



North America. 781). 



687. Agabus brevicollis, Lee, M.C. — Late ovalis, subdepressus, vix nitidus, niger, 

 antennis rufis, pedibus piceis ; elytris densius profunde reticulatis, pone medium 

 versus latera guttula ferruginea. Long. \Q\, lat. 6l m.m. 



I have seen but a single individual, a male in very decayed condition, of this very 

 distinct species ; it is of a very broad flat form, with the thorax continuing the 

 outline of the elytra with very little interruption, the lateral margin of the thorax 

 is broad and but little raised ; this male has the front and middle tarsi moderately 

 incrassate and furnished beneath with glandular hairs, the claws are broken. 



North America, (California). 802. 



Group 4. 



The single (European) species forming this group has the characters similar to 

 those of the highly developed members of group 2, except that the swimming legs 

 are highly developed, being short and thick. 



G8S. Dytiscus brunneus. Fab., Agnhus hninneus, M.C — Ovalis, latiusculus, sat 

 convexus, nitidus, Isevis, subtus niger, capite prosternoque ferrugineis, medio nigris. 



