Western China and Eastern Thibet. 305 



doubts as to whether the abdomen and head of the original 

 male type of infuscata might not have been accidentally 

 broken off and replaced by that of some other species. It 

 appears to me practically certain that Th. infuscata and the 

 var. fastigiata are specifically identical and distinct from erotica. 

 I can state positively that the head and abdomen of the 

 original male of infuscata have never been detached and also 

 that the two small steel-blue spots are present (contrary to 

 what is stated in the original description) and less rudimentary 

 than those in the original female type. Furthermore, I have 

 since received another male agreeing perfectly with the 

 original in wings, genitalia, and appendages, but in this 

 individual the two steel-blue spots are absent. 



Thecadiplax is made up of incongruous materials, and it is 

 probable that the large and ponderous Th. baccha, Selys, may 

 form a group by itself; of this the female is at present not 

 known to me, but 1 possess three males taken by Mr. J. J. 

 Walker in the Chusan Archipelago and vicinity. 



Here, also, I allude to the solitary male insect from Ta- 

 chien-lu mentioned in my former paper (p. 432) as " Agriono- 

 ptera(?), sp." In this insect there are symmetrically two 

 nervules in the median area ot the posterior wings (one 

 forming the inner triangle and one other), and in the same 

 wings the arculus is symmetrically not coincident with the 

 base of the triangle, but placed distinctly (though not distantly) 

 more towards the base. These characters induced me to think 

 of Agrionoptera as a possible, though doubtful, location. 

 Further examination causes me to think its position is near 

 Thecadiplax infuscata, although the characters just alluded to 

 are foreign to such a connexion. The general form is not 

 opposed to such a position : there are only ten antenodals (the 

 last not continuous) ; the extreme apex (after the end of the 

 pterostigma) of all the wings is infuscated, and the genitalia 

 and appendages do not apparently differ from those of Th. in- 

 fuscata. The top of the face is unspotted (the form of the 

 prothorax it is not now possible to define). Whether this be 

 a case of individual aberration, or whether it is indicative of 

 a group in which there is plasticity of neuration as well as of 

 other characters usually considered essential, further materials 

 can alone decide.] 



Orthetrum internum, M'Lach. 



nicum, var. internum, M'Lach. Ann. 

 431. 



In my former paper I gave certain characters separating 



Orthetrum japonicum, var. internum, M'Lach. Ann. & Mag. Nat. Hist. 

 May 1894, p. 431. 



