a carnivorous Tipulid larva. 239 
all below the spiracles. The posterior pair are very long 
and tapering, and extend far beyond the rest of the body. 
Each encloses a good-sized trachea. On the under side 
of the same segment are two pairs of appendages, each 
consisting of a base and two joints. The anus opens 
between the anterior pair. 
Such caudal appendages are usual in the larve of 
Tipulide, and occur also in some other Nemocera. I 
have to thank Baron Osten Sacken for the following 
remarks on this subject :— 
“The caudal appendages of the larve of Tipulide 
which I have observed are of two kinds :— 
“1. Processes above the stigmata. These are found 
in the larve of Tipula, Pachyrrhina, and of some (not 
all) of the Ctenophore.* There are usually two pairs, 
sometimes three. They can be contracted at pleasure, 
and when contracted they serve to protect the stigmata. 
They are often strengthened by small horny patches on 
the posterior side. The larva of Dicranota has no pro- 
cesses of this kind. 
“2. Processes below the stigmata. These may be 
either in front of or behind the anus. In the monograph 
of ‘North American Diptera,’ iv., p. 7 (1869), I men- 
tioned soft, digitiform, retractile processes, which I had 
noticed in some larve of an unknown North American 
Tipulid ; they were inserted in three pairs in front of 
the anal aperture, and resembled those figured by 
Réaumur (vol. iv., pl. xiv., fig. iv.) ; later, in my studies 
on Tipulide (ii., p. 166, Berl. Ent. Zeit., 1887), I con- 
sidered them as ‘branchial appendages.’ Your Dicranota 
larva also has three pairs of appendages, all of which, 
as you discovered, contain branching trachee. The 
difference lies in the fact that in your larva the two 
anterior pairs of appendages are jointed, and one pair 
is placed in front of the anus; while the third pair, 
placed some distance behind, is caudal.’ + 
* C. pectinicornis and C. bimaculata have them, but C. atrata 
(subgenus Xiphwra) has not. (Studies on Tipulidae, pt.i., p. 173.) 
} ‘Since my publication of 1869 many descriptions and figures 
of larvee of Tipulide have been published, which show a variety 
of appliances for breathing under water. 
“In 1875 Grobben (Herzbildung von Ptychoptera, Sitz. d. Acad. 
d. Wiss., Bd. Ixxii.) gave the name of tracheal gills (‘kiemen- 
tracheen’) to a pair of appendages at the base of the breathing: 
tube of the larva of Ptychoptera (fig. 1, kt.). 
