Misce Han eous. 429 



On a n»w Genus and Species of the Family Troehilidee. 

 By John Gould', F.R.S. &c. 



I must confess that, after the many years I have been studying 

 this family of birds, I was not prepared for the acquisition of the 

 very remarkable species hereinafter described. It is most nearly 

 allied to the members of the genus Thalurania, but is sufficiently 

 distinct in its form to warrant its being constituted the type of a 

 new genus, for which I propose the name of Hylonympha, with the 

 following characters : — 



Bill stout, somewhat curved, a little longer than the head. Wings 

 rather long and falciform. Feet and toes moderately strong ; tarsi 

 clothed. Tail ample, deeply forked, and larger in comparison with 

 the size of the body than that of any other member of the family. 



Were it not for its large, long, swinging tail, it would very much 

 remind us of Thalurania glaucopis. 



Hylonympha macrocerca. 



Crown of the head glittering blue, with a reflection of green 

 towards the edges ; throat glittering green, passing into dull green on 

 the flanks ; abdomen black, glossed with green ; feathers clothing the 

 tarsi dark brown on the outer side and white on the inner ; under 

 tail-coverts black ; all the ten feathers of the tail, the outer ones of 

 which are very broad, a uniform steel-black. 



Total length 8| inches ; bill 1, wing 2|, tail 6, tarsi |. 



Habitat uncertain. I obtained this bird from Mr. Whitely, who 

 stated he received it in a collection of skins which had been formed 

 in Brazil. 



On the Zoological Position and Function of the Parasitic Acarina 

 called Hypopus. By M. M£gnin. 



In a recent note I announced : — 1, that under my eyes an octopod 

 nymph of Tyroglyphus rostro-serratus had been transformed into a 

 Hypopus easily recognizable as H. feroniarum, L. Dufour ; and, 2, 

 that I had seen the same Hypopus under different conditions resume 

 the form of Tyroglyphus. From these facts I concluded that the 

 Hypopodes, and their analogues the Homopodes and Trichodactyli, 

 were merely transitory asexual states of the Tyroglyphi and perhaps 

 of other Acarina. I have now to announce further observations, 

 which fully confirm the previous ones. 



In a large undescribed Tyroglyphus, which also lives upon fungi, 

 but feeds chiefly on the stalk (whilst T. rostro-serratus particularly 

 affects the hood and the lamellae), I have also seen the asexual 

 nymph become transformed into a Hypopus. This Hypopus, which 

 is much larger than the former one, appears to be the Acarus spini- 

 tarsus, Herm. ; it is of the same size (0*33 by 0-12 millim.) and of 

 the same orbicular oval form. Its legs are robust, furnished with 

 claws without suckers, and provided with numerous rigid setae, 

 especially posteriorly ; it is cuirassed like the other Hypopodes, is of 

 a rose colour, with a pair of vesicles filled with a bright green liquid, 



Ann. d- Mag. N. H. Ser. 4. Vol. xii. 29 



