760 



Extracts from lettres regarding Brazilian caddis-flies. 



from Brauer's description. The lateral tubercles of the first segment of the ab- 

 domen are beset with pairs of microscopical spines. In describing the legs of 

 the pupa, Brauer says that the skin of the pupa bears but few hairs; if indeed 

 the fore and middle legs of the pupa were hairless, or nearly so, H. ceylanica 

 would probably not live in the water, but on wet places, where the pupa is not 

 obliged to swim. According to Brauer there should be a pair of horny plates, 

 armed with hooks, on the back of abdominal segments 2 6; in our species these 

 exist only on segments 3 6, but there is a second pair on segment 5, with the 

 hooks curved in an opposite direction. Brauer's figure of the apex of the ab- 

 domen shows it as deprived of appendages. I cannot help thinking this must 

 be an error; all our species have well-developed appendages bearing the usual 

 four long hairs. 



"The pupse of a species of Hydropsichida- living on the same rocks here 

 likewise have hairless legs, and this is also the case with the species of Lepto- 

 ceridce which inhabits Bromelice, while, in a closely allied species J ) living in 

 rivulets, the hairs on the fore and middle feet are well-developed, as you will see 

 by the pupa-skins I send you. 



"Of the other species I send you, one agrees in almost every particular with 

 Brauer's description of the New Zealand genus Tetracentron, so that I presume 

 it will belong to that genus 2 ). The larva lives in hollow sticks of wood; but, 

 where the black Dentaliuni-\ike tubes abound, it sometimes usurps the tubes of 

 this latter species. The tubes described by Hagen (Stett. entom. Zeit, 1864, p. 226, 

 No. 23) as Leptocerus? gruinicha, Vallot, must have been inhabited by strangers, for 

 they were closed by stones, whereas the legitimate owners make a circular cor- 

 neous operculum, with a subcentral opening. Though these black tubes are ex- 

 tremely abundant in some places, I have only a few ill-preserved insects, which 

 I hope to replace by better ones 3 ). 



"There is another smaller species which also lives in the tubes made by 

 different Trichoptera, and which has the curious custom of fixing to the mouths 

 of the usurped cases sticks of wood. Even to a practised eye it is often difficult 

 to discover them among the irregular straggling sticks. I have not yet bred the 

 insect of this species, but judging from the structure of the larvae it must be 

 nearly allied to Tetracentron. 



"Hydroptilidcc. The cases of my former letter, which you were inclined 

 to doubt as belonging to Trichoptera, are those of Hydroptilidce. I have often 

 reared the imago. The family appears to be very rich here. I already know 

 the larvae of eleven or twelve species. The most curious of them are two species 



1) This insect belongs to Section iv. of Leptoceridce, according to the system adopted in my 'Revision 

 and Synopsis of European Trichoptera'. It probably forms a new genus allied to Anisocentropus and 

 Ganonema. The cases of it, and of that inhabiting the Bromeli<z, are formed of large pieces of leaves 

 (or entire small leaves) attached flatly in a longitudinal manner. - - R. M'L. 



2) It does agree with Tetracentron in almost every particular. - - R. M'L. 



3) These black tubes have probably been described as actual shells of Dentalium. Vallot (Mem, 

 Acad. Dijon, 1855) cites doubtfully Dentalium corneum, Gmelin, which has since been referred as the 

 case of a Trichopterous insect, as identical therewith, and renames it Phryganea grumicha. The insects 

 sent by Dr. Fritz Muller belong to the Leptoceridcc, but to an undescribed genus of uncertain affinities 

 R. M'L. 



