70 BIOLOGICAL SOCIETY OF WASHINGTON. 



9. Psylla annulata Fitch. 



10. Pachypsylla (n. gen.) venusta, Osten-Sacken. {Psylla 



venusta O.-S.; Ps. c.-grandis Riley.) 



11. Pachypsylla celtidis-mamma, Riley. (Pyslla c. -mamma, 



Riley.) 



The sub-family Psyllinae which is characterized by prominent eyes, 

 short petiolus cubiti, and by the frontal cones (when present) being 

 well separated from the vertex, seems to be well represented in our 

 fauna, but a large portion of our species cannot be included in the 

 European genera. Of the ten genera into which Low has divided 

 the Psyllinae, I have only been able to recognize two in our fauna, 

 viz : Calophya Fr. Low, and Psylla, as restricted by Low. The 

 former genus includes our two Sumac Psyllids, and a third of un 

 known habits, but presumably also living on Rhus. Of Pyslla a 

 moderate number of species are in my collection, indicating the oc 

 currence of the genus on both slopes of our continent. 



Of the four new genera which I have recognized in our fauna, the 

 most interesting appears to be that which includes our Hackberry 

 Psyllids, interesting not only because of the peculiar structural 

 characters exhibited in the larva and imago states, but more espec 

 ially because of the fact that they are true gall-makers. I have 

 called this new genus Pachypsylla, and append descriptions of it and 

 of the principal species which it embraces. 



IV. SUB-FAMILY TRIOZIN^E. 



Next to the Liviinse this is the best defined sub-family of Psyllidse, 

 and it is at once recognizable by the prominent eyes, the long dor- 

 sulum and the absence of the petiolus cubiti. It includes the 

 following species described from our fauna : 



12. Trioza tripunctata, Fitch. {Psylla tripunctata Fitch. 



synonym : Psylla rubi Walsh & Riley.) 



13. Trioza magnolia, Ashm. {Psylla magnolia Ashm.) 



14. Trioza diospyri, Ashm. (Ps. diospyri Ashm. ) 



