152 GEO. H. HORN, M. D, 



consequently diverse opinions have been expressed regarding its sys- 

 tematic position. The most striking peculiarity at first sight is their 

 form. They resemble anything else but Geodephagous Adephaga, 

 while on the contrary, without an examination of the legs, any of the 

 species of Sphalloviorpha or Silphomorpha would be considered aqua- 

 tic entomophaga related to Gyrinus. This similarity has been adverted 

 to by Westwood (^Trans. Linn. Soc. xviii, p. 409), in an interesting 

 paper on relations between various families and orders of insects, in 

 which several new genera and species were described, and those of a 

 form still more removed from the type of Carabidaj than Fsfudomorpha. 

 Adelotopus is, however, the most abnormal, not only in form but also 

 in structure as seen notably in the antennje. The idea that these in- 

 sects should constitute a family apart of equal value with Carabidie, 

 DytiscidfC and Gyrinidoe, has been put forward by Mr. E. Newman, 

 {^Entomolog ist , p. 305, et seq.) without stating any special characters, 

 mentioning only that, as PfteudomorpJia is the first genus described, 

 its characters should be those of the proposed family. Westwood, ]ja- 

 cordaire and others dissent from the opinion of Newman, and prefer to 

 retain the Pseudomorphidte among the Carabidfe as a tribe, though 

 equally out of place wherever it may be interpolated. 



Certain peculiarities in these insects have been pointed out by Dr. 

 LeConte {Clans. Coleopj. N. A. -p. 15), which. appear to have been 

 overlooked by the European writers such as the form and position of 

 the eyes and the form of the posterior coxae. The eyes are more or 

 less irregular in outline, either truncate on one side or angulated. 

 They are really confined to the upper side of the head ; for the mar- 

 gin of the head appears to dip down under the eye and form a floor 

 to the eye. The margin of this plate is at times thickened, as in Ade- 

 lotopus., and appears to be a canthus dividing the eyes into two, as in 

 Gi/rinus. The error of considering the eyes double is still further 

 aided by the smoothness of this portion of the head under the eyes. 

 ]jacordaire allowed himself to fall into the error of describing the eyes 

 of Addotopns as being divided into two by a slender canthuS. 



The posterior coxae show considerable divergence from the true Ca- 

 rabideous type, being contiguous on the median line and of a form 

 more nearly resembling the Dytiscidjc. The articular lobe is narrow, 

 and the points with which the thighs are articulated are at the tips of 

 these lobes, and more nearly approximated than in the Carabidae. In 

 the Carabid;T3 the articular lobe is broader, and permits the femoral ar- 

 ticulation rather externally than at the tips. 



