a Genus of Dipterous Insects. 309 



("rostgelb" in the description, "ferrugineis" in the specific character given by 

 Wiedemann), and that not only the posterior but all the tibi£e are pitchy- 

 black ("pechschwarz") with the anterior femora clavate and the tibiae somewhat 

 arched : Wiedemann, however, has been careless enough to omit the colour of 

 the spines of the thorax in the specimen which he examined from Africa. As it 

 is evident that Fabricius entirely disregarded the Linnsean description, in which 

 the scutellar spines are mentioned as "Jlavce" but described these spines as 

 either red or black, varying, probably, according to sex, it would seem that 

 he did not introduce the rufous colour of these spines from the Linnsean de- 

 scription, but from an actual examination ; and as such a variation is clearly 

 not sexual, it appears to me that he confounded two distinct species with clear 

 wings, and consequently both different from the Linnsean species, under the 

 name of the latter. Moreover, as Wiedemann has not noticed the colour of 

 the spines in the African species, we may perhaps consider that they are of 

 the general colour assigned to the insect, namely, piceous ; in which case, the 

 variety described by Fabricius with red spines would in all probability be the 

 insect from Sumatra, and consequently a species distinct from any described 

 in this memoir. 



Sectio IV. Alcefasciis integris. 



Species 19. Diopsis Dalmanni. fVied. 



Tab. IX. Fig. i;. 



Ferruginosa, alis fuscatis limpido fasciatis. 



Long. Corp. lin. 3. In Mus. Westennann. 



Habitat in Java. fVied. Illustr. Gen. Achias. 



IViedemami, Auss. Zweiji. Ins. vol. ii. p. 560. No. 4. tah. lO'.y. 4. 



Lsevis, juxta scutellum colore flavido abdominisque parte apicali dilatata fus- 

 cescenti tincta. Aloe in medio obscurfe fuscescentes, basi apiceque pallidi- 

 ores, subfuscescentes, in parte obscuriori pone medium alae fascia hyalina 

 exstat e tribus maculis magnis composita, macula intermedia inter nervos 

 Sum et 4um paull6 basin versus alae extensa ; inter medium et apicem alae 

 fascia altera recta vix conspicua hyalina, atque juxta nervum intermedium 

 transversum fascia tertia latior adsunt. Pone et subtus scapulas utrinque 

 spina brevis et subobtusa adest, pone quam altera brevior et vix conspicua 



2 s 2 



