26 DIPTERA OF NORTH AMERICA. [PART IV

forceps,

and

in

many

cases the antenna, has

been

noted

down by

me, almost invariablyfrom livingor fresh specimens.

At

the

end

of the Tipulidsebrevipalpi Iplace the

two

sections

which

I consideras intermediate

between them and

the T. longi- palpi

(compare

above, p. 19)^: the

Cylindrotomina and

PiychojJ- terina

:

—

Sect. VII. Cylindrotomina. Onesubmarginalcell; firstlongitudinal vein incurved at the tip towards the second, instead of ending in the costa (exception^: Phalacrocera replicata Lin.,where the first vein takes theusualcourse);four orfiveposteriorcells; a discalcell;theauxiliary veinisabruptlyinterrupted before the stigma,without ending either in thecosta,or inthefirst longitudinal vein. Eyes glabrous. Normal

num-

berof antennal joints sixteen. Tibise with spurs at the tip. Empodia

distinct. Structure of the forceps and the ovipositor peculiar and characteristic.

Sect. VIII. Ptychopterina. Onlya single longitudinal vein posterior totliefifthvein; two submarginalcells.

Labium

largelydeveloped;palpi long. Tibiaewithspurs at thetip.

After

having

given an accountofthedistribution into sections, I

have

to

add

a

few words on

the genera. I

am opposed

to a too great multiplication of the genera,

and

I believe that as the contrast

between

large

and

small

groups

exists in nature, it

should also be brought before the eye in the classification. In the

genus

Erioptei^a, for instance, the relationship of the

groups which compose

^it is a

much more

striking feature than the characters

which

separatethese groups. If

we

set

up

the

groups

as genera, with only three or four species in each, the difference

between

the large group,

now

called Erioptera,

and

smaller groups, suchfor instanceas the genera

Gnophomyia,

Trimicra,

and

allthegenera of the

group Limnohina anomala,

this differ- ence, so strongly

marked

in nature,

would remain

unexpressedin the system. Subdivisionsof the larger

genera

should of course

be

carefully

marked,

butlessstronglythan the intervals

between

the smallgenera,

and

in suchcases a subgeneric subdivision

may be

useful. This is the course

which

I

have

followed.

6.

General remarks on

thestructure

of

the Tipulid^^ebrevipalpi.

Inthis

paragraph

I

do

not intendtoundertake a general

com-

parative description of the external structure of the Tip. brevi-

I

INTRODUCTION, 2t

valvi

My

^{purposeis, to give areview} of those characters only,

which

have

been

^{used in the} classification,

and

to furnish

some

explanations necessary^{forthe better}understanding^{of the} present

monograph. .,•«.! ^

The

organs ^of the

mouth

of the Tip. brevzpalpi ^afford

com-

paratively

few

characters^{for the}classification.

The

prolongation of the

head

^{in front, called the}

rostrum (compare

Ilonograph,, etc

Vol

I, p. xiii) is generally shorter here than in the 2.p.

longipalpi; ^{it is} considerably prolonged ⁱⁿ tl- genera

i^mm-

phidla, Toxorrhina,

and Elephantomuia, and

^{then beai. the} palpi at its tip.

The

outer envelope ^of the rostrum

has some-

times the shape ^of a short tube ripped

open on

the

under

^sice;

often, however, it is hardly tubular ^{at all,}

but

^{has rather the} appearance ^of a labrum,

and

is either short

and

stout, or long, narrow,

and

linear

(Geranomyia). Whenever

^I

^wanted

^{todes g-} nate this outer envelope of the

rostrum

separately, as

an

inde-

pendent

organ, I

have

called ^itepistoma.

The

^{probosctsconsists}

chiefly of the

under

^{lip, with its suctorial flabs; itprojects}

more

or ^less

beyond

the epistoma; the flabs are usually

somewha

pubescent, ^{linear inthe}

Limnohina, more

^stout

^and

^fleshy

m

^the

LimnopJuUna, ^Amalopina,

^{etc.; (in}

Geranonujia

^the

under

^{lip s} very

much

^prolonged

^and

^{bilobed, the lobes being likewise}

long

and

^linear)

The

palpi incurved

backwards, when

at rest, are four-jointed; a fifth joint,

sometimes

perceptible at tbeir basis, probably represents arudimental maxilla^;

Mr. Westwood

^(Introd.

etc II

P

^525),

who ^makes

^thissuggestion, adds,thatthetexture of thisfifth joint is different

from

that of the other^four.

The

last joint of thepalpi is usually longer thanthe preceding,

som

^-

wha

linear; but, except in

some

rare cases, as

"^

.^/^f

•'«'/

/^

Tever

very^long.

Immediately under

^{the part}

which

I ^call the epistoma,is alinear,pointed organ, ^{called the} tongue;itis espe- ciallylong in

Geranomy... Meigen

^(Vol.

^VI,

p-

28),

^{in d. t} ing the

mouth

^{of Glochina,also}

^mentions

^{a pair of hoiiy,}

lui ar pointed maxiUse.

A

comparative studyof the parts of the

mouth

of the

TipuUdse

^{is yet to}

be made.

The

eyes are oblong or rounded, separated ^a!,ove

by

a fiont

which

is

more

or less

broad

in different genera but not percep- tibly broader in one sex than ⁱⁿ the ^other.

On

the ^uncle

de

of the head,the eyes are usually

more

approximate,^often

almo

^t contiguous.

There

is

no

^{striking difference in the size of the}

28

^]:)TPTERAOF

NORTH AMERICA. [PART

IV.' facets of the

upper and

of the lower part of the eyes, nor a dis- tinct dividingline

between

them.*

The

eyesareglabrous, except in the

Amalopina and

inthe

genus

Trichocera,

where

they are pubescent. Ocelli are

wanting,

except in Trichocera,

where

they are distinctl}'^perceptible;

Pedicia

also

shows some

traces of them.

The

antennae are

composed

of a cylindrical, elongated first joint; ashort,cyathiformor

rounded

secondjoint,

and

from*12 to 14jointsof the flagellum.

The Anisomerina have an abnormal number

of joints (from 6 to 10)^;

and

in

some

foreign genera,the

number

of the joints is larger

(compare

Gi/7iopUstia, Cerozodia, Ctedonia, etc.).

The

usual

measure

of the

antenna

is,that

when

bent backwards, they nearly reach the root of the

wings

; they are

much

shorter than this inthe

genus Amalopis. The male

sex in the

Anisomerina,

especially in

some American

species of Eriocera, has

enormously prolonged

filiform antennae,

sometimes

three orfour times the length of the body.

Some

Limnophilee, also Cylindrotoma,

have

the antennaj of the

male

considerably longer than those of the female

and pubescent

on their

whole

length; usually, however, this difference in length

between

the sexes is

much

less perceptible.

The male

has often, onthe

under

side of the three or four basal joints of the flagellum, a dense, short pubescence,

which

is

much

less perceptible in the female_; in

some

casesthis pubescence extends

on

both sides of the

whole

antenna. It is worthy^ of notice that

when

the antennse ofthe

male

ai'e long

and

pubescent, the first basal joint is very aptto be shorter

than

usual; this is the case for instance with

Limno- phila

tenuipes,

Cylindrotoma americana,

Ula, etc. Pectinate antennae occur only in

Rhipidia among

the native species, but severalforeign

Limnophilina have them

^also.

The

feet are long

and

slender,

more

or less pubescent^; the presence or absenceof spurs atthe tip of thetibiee, of

empodia, and

of teeth

on

the underside of the

ungues

constitute the basis of the principal subdivisions of the T. hrevipjalpi,

and

will be sufficientlynoticedbelow.

The

^spurs,

whenever

present, are

two

' In thegenus Blepharocera (fam. Blepharocerld(v,Monogr. Vol. I,p. 8) the eyesaredivided intwoportions, the upper one with ^large, thelower one with smallfacets; theupperportion is comparatively smallerinthe malethan in thefemale; inlife,these portionsdiffer in their color; the npperone, inB. capitata Lw.,isreddish-green,the lower onepurple.

INTRODUCTION. 29

in

number

on each^tibia,

and

occur

on

all thethree pairs oftibice;

I

have

not observed a single caseof spurs occurring

on

one or

two

pairs of tibite only.^

The

last tarsal joints

show

a sexual character, the very general occurrence of Avhich has, I believe, notbeen observed before: inthe male, the interval

between

the last

and

the penultimatejoint isexcised

on

the

under

side,

which

enables this joint to be bent

under

the preceding (a similar structure in a

Tipula

is figured

by Westwood

inAValker's Ins.

Brit.Dipt. Tab.

XXYIII,

fig. 5 d). In suchcases the lastjoint itself is modified in its structure, generally

more

elongated, slender,

somewhat

curved,

and

beset

with

bristles

on

the

under

side. This structure prevails through nearly all the genera, although itis

sometimes wanting

in single species of a

genus

in

which

it otherwise prevails.

The

prothorax(collare) varies in breadth

and

the

remaining

parts of the thorax in shape.

These

modifications, although

mentioned

in the descriptions,

have

not served to establish

any

important subdivisions.

On

the front part of the

mesonotuni

there is often a pair of black dots,

one on each

side,

immedi-

ately

back

ofthe

humerus

;

sometimes

they

assume

the appeai*- ance ^of small pits, with a

brown

or black, shining bottom. I

do

not

know what

they are; they

may have some

connection with the prothoracic spiracle,

which

is not farfrom them, immediately below.

There

is

no

vestige of

them

in

some

species

and

genera (for instance in

Pedicia and

Amalopis). In other cases, they arequiteconspicuous, asinthe

group

ofLimnophilae, represented

by

L. luteipiennis.

These

latter species have, besides the pits,

two

closely

approximated

shining dots, black orbrown, near the point of contact of the intermediate thoracic stripe

with

the collare.

The abdomen

isnine-jointed_; the eighthjointis often

narrow

_; the ninth usually consists of an

upper

half

segment and

of the genitals.

The

external sexual apparatus of the

male

consists of aforceps,

by means

of

which

the

end

of the female

abdomen

is seized

from

below, a little before the ovipositor, in such a

manner,

that the latter

organ

is stretched out

on

the

upper

part of the

abdomen

of the male. Thisdone, the

male

with a second, inner, clutching apparatus seizes the orifice of the inner genital

' Atarhamay,perhaps,form an exception; compare thisgenus.