32 U. S. P. R. R. EXP. AND SURVEYS ZOOLOGY 47TH PARALLEL. 



dehiscent, and the mesosternum at the tip compressed and carinate as in Notiophilus. From 

 the latter genus it differs by the very short emarginate labrum, by the more distinct, but also 

 bicuspid mentum-tooth, and by the less prolonged prosternum. Of the anterior tarsi of the 

 male, the first and second joints are dilated ; the third and fourth are small an equal. 



AMPHIZOIDAE. 



Coleoptera pentamera, pedibus ambulatoriis, antennis filiformibus; prothoracis episternis a 

 noto sutura divisis, acetabulis anticis postice hientibus ; coxis anticis et mediis globosis, posticis 

 transversis ad marginem corporis extensis, contiguis, antice truncatis, postice ad insertionem 

 pedum elevatis ; mento magno emarginato, cum gula omnino connate, (sutura nulla ;) maxillis 

 lobo interno curvato acuto, intus parce spinoso, galea elongata palpiformi exarticulata ; abdo- 

 mine sex-articulato, articulis anterioribus tribus connatis. 



In the above diagnosis I have placed an assemblage of characters which seem fully to justify 

 the establishment of a separate family for the reception of the very remarkable Amphizoa 

 insolens. A detailed description may be found in the 6th volume of the Proceedings of the 

 Academy of Natural Sciences of Philadelphia, (p. 227;) I there express the opinion that it would 

 not enter any family of Adephaga as then constituted, and brief allusion was made to the large 

 size of the posterior coxae, which cut off all connexion between the metathorax and the ventral 

 abdominal segments, as indicating an affinity with the Dytiscidae, a view which, also, seemed 

 to be confirmed by the subglabrous antennae ; at the same time the ambulatorial legs showed a 

 tendency towards the Carabidae. Since there appeared to be, however, no very strong resem 

 blance in the structure of the legs, though ambulatorial, with those of Carabus, I did not insist 

 very strongly on the latter affinity. 



Lacordaire has, in the excellent work now being published by him on the Genera of Coleoptera, 

 (Vol. 1, p. 409,) introduced an abstract of the description given by me, but not considering 

 the characters sufficiently important to define a new family _, has placed the genus as a tribe of 

 Dytiscidae, equal in value to Pelobius. A misunderstanding of some expression used by me 

 has, unfortunately, led him to place in the diagnosis of the tribe, hanches posterieures . . 



non contigues au cote interne; which is not the case ; the coxae come 



together on the median line, as in Pelobius, Dytiscus, &c., but differ in the anterior margin 

 being transverse and rectilinear, while in all true Dytiscidae (Haliplus and Cnemidotus being 

 excluded) the anterior outline is rounded ; the posterior lobes above the insertion of the hind 

 feet are more distant and less elevated. The second ventral segment is prolonged anteriorly 

 in an obtuse angle, and articulates with the coxae, so that the first segment is entirely lateral, 

 as in Carabidae. From this it results that no part of the metathorax reaches the ventral 

 segments of the abdomen, all communication being cut off by the coxae extending to the sides 

 of the body. 



Another character not found in any other Adephagous insect, is the complete union without 

 any visible suture between the gula and mentum ; this fact is of great importance, and upon it 

 the argument for the separation of this as a new family must to a considerable extent rest. I 

 regret that it was omitted in my former description, although observed while making a re- 

 examination for the present report ; to Dr. Schaum, also, I owe my acknowledgments for a 



