610 Recent Literature. [ June, 
sule (kiefer-kapsel), supporting some of the mouth-parts, and con- 
taining the cesophagus. Less important characteristics are then 
enumerated. A very unsafe character is the number of visible 
body-segments, since in some they are often not true segments, 
but intermediate rings arising from the lengthening of the mem- 
brane connecting the true segments (Polytoma); in others a sec- 
ondary annulation of the single segments, whose true limits in 
the living animal can be best determined by the markings rè- 
peated on the true segments (Ceraplatus); or they appear to be 
reduced in number through the coalescence of the anterior of 
hinder segments (Blepharocera, Liponeura, Culex, Simulium, etc.); 
or any external segmentation is almost wholly wanting ( 
Microdon, etc.). : f 
Thus we may count in the Polytomous larvæ behind the max- 
illary capsule (we do not know how better to translate Arefer np 
sel) 20-21 segments ; in the Cecidomyid larvæ 13 segments; 1 
the Tabanidæ and Stratiomyide 11 segments; in the sere 
11-12; in the Tipulide 12, as also in the Asilide, Nemestrin 
and in the Muscidæ. 
“In the Muscidæ, Æstridæ, etc., the larval body is jia 
12-segmented. This is based on the view that the anten 7a 
ment enclosing the mandible (mundhaken), which in E 
cyclorrhaphous larvæ remains membranous, while in the bal 
rapha (except Lonchoptera) it is above firm and pape byes 
ing a ring bearing the antennz and jaws, which we aye ion 
the kiefer-kapsel. On the other hand the cyclorrhaphou sť 
ly eleven true Pi 
or antennal segment must especially be rega 
though the terminal segment in a good d 
formed of two segments (Blepharoceride, etc.). di one, and 
While the view as to the head-segments 1S a pra 
of value from a systematic point of view, WE behest 
Brauer has not adopted the broad morpholog that the head 
the well-known facts in the embryology © her insects, i 
of any dipterous insect is at first, like that of ot frst 
posed of four segments, 7. ¢., an antennal, ma dificati 
illary and second maxillary ; the peculiar m0 a: the 
dipterous larvæ being the result of degra varying * g 
tion of form and structure in these larvæ to hak the ed | 
roundings being very sap It see i sae : 
Eucephala (Chironomus, etc.) represen i a : 
dipterous a the headless forms, Or magga ’ aia pot P 
of adaptation. It was, however, Dr. Brauer ee 
enter into these questions in the present essay, 
