AMERICAN COLEOPTERA. 153 



The very narrow separation of the middle coxae, and the connate 

 nientum and gula, are characters not without some value in the isola- 

 tion of the Pseudomorphidae as a separate family. The narrow sepa- 

 ration of the middle coxse is not however a constant character in this 

 family. In the species just described these coxae are as widely sepa- 

 rated as in many species of Platj/nus. 



The form of the antennae of Adelotopux, and the number of abdomi- 

 nal segments in Ili/ilroporomorpha , though very anomalous characters, 

 cannot assist materially in the establishment of the family, each cha- 

 racter being found singly in the genera named. The principal charac- 

 ter, therefore, will be found in the contiguity of the posterior coxae, 

 and the consequent separation of the metasternum from the abdominal 

 segments. 



The relationships of the Pseudomorphidae with the Carabidse and 

 Dytiscidae may be thus tabulated : — 



Legs cursorial. 



Metasternum attaining the abdomen; hind coxae separated. 



Antennae inserted on the front Cicindelidae. 



Antennae inserted under the margin of the front Carabidae. 



Metasternum not attaining the abdomen; hind coxae con- 

 tiguous. 



Metasternal parapleurse attaining the abdomen PseudomorphidaB. 



Metasternal parapleurae not attaining the abdomen. ..Amphizoidae. 

 Legs natatorial. 



Eyes two; antennae filiform Dytiscidae. 



Eyes four; antennae irregular Gyrinidae. 



From the above table it will be seen that the Pseudomorphidae form 

 a link from the Carabidae through Amphizoidae to the Dytiscidae, with 

 undoubted tendencies toward the Gyrinida), and by their removal from 

 the Carabidae tend to render that great family more homogeneous. 



The Pseudomorphidae are contained at present in five genera, and 

 may be arranged as follows : — 



Head horizontal; mouth anterior; antennae filiform. 



Without antennal grooves Pseudomorpha. 



With antennal grooves. 



Mentum entire; ventral segments four Hydroporomorpha. 



Mentum emarginate ; ventral segments six. 



Posterior angles of jirothorax distinct Sphallomorplia. 



Posterior angles of prothorax rounded Silphomorpha. 



Head deflexed, front very convex; mouth inferior ; antennae 



clavate '. Adelotopus. 



. In the monographic notice of these insects, {Rev. et Mag. Zool. 1853, 

 p. 395), Westwood unites the first, third and fourth genera, without as- 



TKANS. AMER. ENT. SOC. (20) JULY, 1867. 



