MAY FLIES AND MIDGES OF XEAV YORK 69 



The larva of 1 1 h y t r i c li i a was originally discovered by a 



Mr Bolton of Birmingham who formerly supplied living 



microscopical material for students, and it was noticed by me 



in Ent. Mon. Mag., 1st series, vol. xxiv, p.lTl (1888) ; it has also 



recently been described by Ulmer (Stett. Entomol. Zeit. 1902, 



p.361). 



7. Ithytrichia confusa, n. sp. 



Antennae about 28-jointed in the (^, long and slender, none of 

 the joints really submoniliform, entirely fuscous, save a few basal 

 joints, which are pale yellow. 



The last segment is open dorsally and within it lies a compli- 

 cated organ represented in fig. 16. The appendages are closely 

 approximated ventrally; in the side aspect they consist of a broad 

 basal part, from the upper portion of which springs a long blade- 

 like process, with rounded outei' margin, beset within with 

 numerous spines or spinous hairs. The outer margin of the basal 

 part is beset with strong incurved teeth. 



This species, which is very easy of identification, is referred 

 provisionally to Ithytrichia, but the form of the append- 

 ages and the long slender antennae isolate it from the typical 

 species of Ithytrichia. It is almost certain to be ultimately 

 regarded as tlie type of a new genus. 



Op.tiiotrichia 



The European species frequent both standing waters and rivers. 

 They are insects which measure from 6-8 mm. in expanse of wing, 

 and McLachlan .says of O. a n g u s t e 1 1 a that its antennae have 

 about 39 joints in the J^ and about 31 in the $. The most promi- 

 nent features in the J* genitalia are as follows : Large dorsal 

 plate which is more or less asymmetrical, usually notched in its 

 outer margin and with stronger chitinized parts, which assume 

 the form of hooks or strong teeth. The penis is of very great 

 length, very slender, apparently divided into two parts, the apical 

 part which probably forms about i of the whole, being probably 

 retractile (according to McLachlan, and I think he is correct). 

 In O r t h o t r i c h i a t e t e n s i i Kolbe, the side pieces of 

 the last segiuent are asymmetrical, on one side being produced 

 into a rather long, slightly curved sub-acute process, the other 



