1881. j 223 



HOMOPTEEA. 

 Fam. MEMBBACIDM. 

 Triquetral intermedia, n. sp. ? 

 Triquetra inermis, Fairm., var. ? 



Closely allied to T. inermis, but differs by the anterior dorsal ridge of the pro- 

 notum being produced into a distinct, compressed, erect, and somewhat anteriorly- 

 directed spine-like process. Length, 14 mm. 



Hab. : Bogota (Dr. Tliihne). Coll.: Oberthiir and Distant. 

 This form is intermediate between T. inermis, Fairm., and T. 

 nigro-carinata, Fairm., and only differs by the following characters : 

 — from the first, in which the dorsal spine is absent or obtusely 

 indicated ; and, from the second, in which the same spine is much 

 more produced. 



As in T. inermis, many specimens exhibit a strong tendency to 



develop prominently this pronotal spine, I should incline to the 



opinion that T. intermedia is only an intermediate form between the 



two other described species (?), and that the three are only phases of one 



protean type. However, I have been reluctantly obliged to give the 



f specimens described a specific name to prevent my treating T. inermis 



and T. nigro-carinata as synonymic, more especially as Stal has 



described another species, T. recurva, in which this spine is even more 



produced, but of which that author remarks : " T. inermi et T. nigro- 



carinatce valde affinis, cornu dorsali ejusque forma divergens ;" and 



also, " In exemplo feminino, specifice haud diverso, cornu lateralia 



| thoracis valde antrorsum et sursum vergunt." This last observation 



U may be probably explained by the law frequently enunciated and 



lately again exemplified in butterflies by Mr. Wood-Mason (J. A. S. 



I B., vol. xlix, p. 418), that secondary sexual characters acquired by the 



I male have been partially transmitted to some females, but not to others. 



As T. inermis, T. intermedia, T. nigro-carinata, and T. recurva, have all 



been received from Colombia, and as they are also distinct from other 



species of the genus in the common character, "Carina dorsali thoracis 



nigra," and their specific differentiation depends on the amount of 



development of the anterior portion of the pronotal dorsal ridge, the 



i probability of them all being but different forms of one protean species 



is much increased, and we may possibly only require larger series of 



specimens to find all the intermediate links. The words of Mr. Darwin 



may be here well applied : " A part developed in any species in an 



extraordinary degree or manner in comparison with the same part in 



allied species, tends to be highly variable." 



Selston Yillas, Derwent Grove, East Duhvich : 

 January, 1881. 



