802 DR. LE CONTE ON PLATYPSYLLID^E. [Nov. 5, 



Mr. Ritsema regarded it as representing a family of the so- 

 called suborder Suctoria, or Aphaniptera, equivalent in value to 

 the Pulicidce, or true fleas. Professor Westwood, on the other 

 hand, viewed its organization as so peculiar that he established upon 

 it a new order of insects, which he named Achreioptera. 



After the detailed description given above of the separate organs, 

 it seems hardly necessary for me to defend my opinion of the Coleo- 

 pterous nature of this object, as against the views expressed by my 

 learned colleagues. It will be better, by an analysis of the characters 

 detailed, and a comparison of the different parts with familiar forms, 

 to show that the peculiarity of Platypsylla consists rather in the 

 assemblage of unusual and rare characters with a further modifi- 

 cation and exaggeration of certain parts, indicating only family 

 value or strange habits of life, than any thing of sufficient import- 

 ance to warrant its reception as a distinct order. No differential 

 characters for his new order were given by Professor "Westwood ; and 

 without very decided modifications in the plan of the mouth, thorax, 

 and wings, profoundly different from those seen in other orders, it 

 would be very inexpedient to rate any species, however odd its ap- 

 pearance, as an equal to the great and important types in nature 

 which are recognized as orders of insects. 



The structure of the mouth, the size and mobility of the prothorax, 

 the presence of elytra, the arrangement of the sternal surface, and 

 the insertion of the legs, all forbid, in the most positive manner, its 

 reference to the Aphaniptera, or any allied series of insects. 



In comparison with other families of Coleoptera the mentum is 

 altogether peculiar in form ; but an approach to it is found in Lep- 

 tinus, a singular genus also subparasitic in its habits. It has been 

 usually classed with Silj)hidce ; but in examining a species found in 

 North America, I thought the form of the mentum, with other pecu- 

 liarities, sufficient to warrant its reception as a distinct family, Lep- 

 tinidce (Le Conte, Proc. Acad. Nat. Sc. Philadelphia, 1866, p. 368). 

 The mentum, in fact, is large, subquadrate, and the hind angles are 

 produced over the gula in long spiniform processes, the feebly deve- 

 loped analogues of the triangular wing-like processes of Platypsylla. 



The ligula and labial palpi present nothing wortlry of note ; the 

 maxillae also are of not unusual form in various parts of the Clavicorn 

 series ; the strong corneous stipes and cardo resemble more nearly 

 those of Trichopterygidce than any other family. 



The form of the mandibles is entirely that of Corylophidee. 



The labrum is peculiar from its great breadth as compared with 

 its length. I do not remember to have seen any figure resembling it. 



The head is peculiar in form, from the deep groove behind the 

 occiput, between it and the front margin of the prothorax, and still 

 more wonderful on account of the posterior comb of short, flat 

 spines, — a beautiful adaptation to the habits of the animal, enabling 

 it to glide always forwards amidst the dense fur in which it lives — 

 a movement which is also facilitated by the fringes of hair on the 

 hind angles of the head and prothorax, the edges of the sternal 

 plates, and the long spines of the tibiae. 



