268 NORTH AMERICAN TRYPETINA. 



the strikingly large transverse diameter of the short ovipositor; 

 but, like Trypeta Macquartii, it agrees with the true species of 

 Wiagoletis in the coloring and in the picture of the body, so that 

 I prefer, for the present, to leave it in that genus. It may be 

 objected that, in this case, I lay a greater stress upon peculiari- 

 ties of the coloring and mere differences of habitus than upon 

 plastic characters. In answer to this objection I may state that 

 I fully appreciate the value of plastic differences in matters of 

 generic grouping of species, but that the knowledge of the exotic 

 Trypetse, as well as the existing descriptions of them, are not 

 sufficient for their geueric distribution upon plastic characters 

 only. Most descriptions mention but very little about these 

 characters, the more so as in most cases they have to be drawn 

 from a few indifferently preserved specimens, which do not allow 

 a sufficiently clear view of such characters. And thus it happens 

 that peculiarities of coloring and other habitual characters become 

 in many cases very useful for the generic distribution of exotic 

 Trypetse, especially in cases where the only available plastic 

 characters are of a very delicate nature and hence more difficult 

 to perceive. It is true that the exotic species thus treated are 

 merely grouped, and not systematized ; but this grouping in itself 

 is a progress towards the determination of the species, and is one 

 of the usual steps towards a systematic distribution. 



26. T. insecta Lw. J. (Tab. X, f. 8.)— Thorace nigro, capite, 

 abdomine pedibusque luteis, alarum nigrarum incisuris marginalibus, 

 guttulisque inter venaruin longitudinalium tertiatn et quartam tribus 

 vel quatuor pellucidis, vena longitudiuali tertia nuda, setis scutelli 

 duabus. 



Thorax black ; head, abdomen, and feet clay-yellow ; wings black, with 

 hyaline indentations along the margin and with three or four hyaline 

 drops between the third and fourth veins; the third vein not bristly; 

 scutellum with two bristles. Long. corp. 0.14; long. al. 0.14. 



Syn. Trypeta insecta Loew, Monogr. I, p. 72. Tab. II, f. 8. 



Hab. Cuba(Poey). [Hayti; P. R. Uhler.— 0. S.] 

 Observation 1. — T. insecta belongs to the typical species of 



the genus Aciura, the scutellum of which bears only two bristles. 



The picture of the wings of this genus is characteristic. 



Observation 2. — Another Trypeta of the same genus occurs 



in Brazil, which may be easily mistaken for Trypeta insecta. I 



prefer, therefore, to describe it here : — 



