166 Mr, R. MacLachlan's Monofjraph of 



yellowish ; the radius and sub-costa alternately blackish 

 and yellowish. The posterior wings marked with blackish 

 at the pterostigma. 



Length of body 7 lines; expanse of wings 20-23 lines. 



This large and beautiful insect is not uncommon in 

 summer about streams. It varys little in size, but to 

 some extent in the number and intensity of the spots. 



A detailed history of the development, and habits of 

 the larva, is given by Hagen, in the "Linnsea Entomo- 

 logica," vol. vii. pp. 868 — 418, pi, iii,iv. The larval exist- 

 ence would appear to last about seven months. The larva 

 does not swim, but rests on or crawls about plant stems, 

 gravel, &c. It can scarcely be said to be truly aquatic, but 

 is rather amphibious ; that is to say, it is able to live both 

 in the water, and among the damp moss, debris, &c., in 

 the vicinity of it. The pupa is contained in an irregular 

 rounded cocoon. The first certain accounts of the habits 

 of this larva, were given by Herr Brauer, to whom Ento- 

 mology is so greatly indebted for his discoveries in Neu- 

 ropterous larvee. 



It will be remarked that I have rejected the Lin- 

 nean name clirysops, and I here give my reasons for so 

 doing. It is true that in the Linnean Collection this 

 insect is labelled "clirysops" in Linnets own handwriting, 

 but a glance at his description of the insect he intended 

 to bear that name, proves that it could not be Osmylus. 

 His words run thus: — "Viridi nigroque varius, alis hya- 

 linis, maculatis reticulatis," and "Musca foetida, auro 

 oculata.^^ A Chrysopa is intended by these, and this is 

 also proved by his reference to Frisch (Insekten Teuts- 

 chlands, vierdter Theil, p. 40, tab. xxiii) who describes 

 the insect under the name of " Der gold-iiugigen Stinck- 

 Fliege,'' 



Genus II. Sis yea, Burmeister. 



Ocelli absent ; antennm about half the length of the 

 wings, the joints rounded, strongly setose; last joint of 

 the maxillary palpi acuminate, pointed, about four times 

 the length of the penultimate. 



Prothorax narrowly transverse, not so broad as the 

 head. 



Abdomen short, moderately robust ; in the male pro- 

 vided with two simple corneous appendices at the apex ; 



