DICRANOMYTA. T3

74

DIPTERA

or

NORTH AMERICA. [PART

IV.

Head

dark brown, antennae

and

palpi black.

Thorax

dark brown,

moderately

shining

and

slightly pruinose "n'ith grayish

above

; stripes notdistinct;

some

parts ofthe pleurae

and

ofthe posteriorportion of the

thorax

are reddish or yellowish-brown.

Halteres with an infuscated

knob

^; feet

dark

"brown,

femora

tawny, paler at the basis; coxjb brownish-yellow.

Abdomen brown

; forceps paler; the

upper

valves of the ovipositor are very narrow^, pointed,

and

nearlystraight.

Wings

(Tab. I, fig.

2) immaculate,

somewhat

tinged with grayisli; stigma elliptical, pale

brownish

; the

apex

of the

wing

is finely

and

sparsely pubescent; in the marginalcell this pubescence begins a little before the stigma,

and

it occupies nearly the

whole

of thesub- marginal, posterior,

and

discal cells.

The

tip of the auxiliary vein is

about one

length ofthe

stigma beyond

the origin of the secondlongitudinalvein; the subcostal cross-vein isnearitstip.

The

first longitudinalvein endsinthe second,forming a regular arQof a circle; the cross-vein connectsitwith the costa.

The

discal cellof this species is often

open (among twenty specimens

caught

by me

in

1859

inthe

same

locality, five

had

it open),

and

insuch specimens,it istheanterior

branch

(and not the posterior

one

as usual) of the fourthlongitudinalvein

which

is forked; in otherwords, the discal cellcoalesces

with

the third,

and

notwith the second posterior cell.

Hab. Washington,

D.

C,

not rare in April

and May;

^also

further north.

The pubescence

in the apical portion of thewing, as well as the forking of the anterior, instead of the posterior

branch

of the fourth vein are very

good

distinctivecharacters of this species.

17. I>.glolJiltliorax,n.sp.

%

and 9^•

—

Brunnea,capiteantennisque nigro-fuscis,thoracegibbo;alisbrevioribus, pallide infuscatis,

immacu-

latis,stigmatis vestigio nullo; vena longitudinali prima in secundam (nonincostam)incurvS,;venaauxiliariponeprsefurcseinitiumextensS,.

Brown, bead and antennae brownish-black; thoraxgibbous,wingsrather short, slightly tinged with brownish, without spots; no vestige of a stigma^; the first longitudinalvein is curved towards the second(not towards the costa); auxiliaryvein prolonged beyond the origin of the prsefurca. Long.corp. 0.2

—

^0.22.

Head,

includingthe palpi, brownish-black;joints of the flagel-

lum

short, subglobular, with a short, scattered pubescence.

DICRAXOMYIA.

75

Thorax

strikingly gibbous, rising abruptly over the

head

; itis

brown, almost

opaque

above, without distinct stripes;

more tawny on

the sides

and

posteriorly; halteres infuscated; feet

brownish

; coxoe

and

baseofthe

femora

pale;

abdomen,

including theanale genitals, fuscous; ovipositorrather short^;

upper

valves distinctly curved.

Wings

comparatively shorter

and

broader than inthe related species, with aslight

brownish

tinge;

no

per- ceptible vestige of a stigma.

The

firstlongitudinal vein, instead of ending in the costa, iscurved at its tip

towards

the second longitudinal vein

and

ends init; thusthecross-vein isapparently placed

between

the first longitudinal vein

and

the costa; the tip of the auxiliary vein, with the subcostal cross-vein close

by

it, is

nearly opposite the

middle

of the pra^furca; the

submarginal

cell is notquite one-third longer than the first posterior; first

and

second basalcells of equallength.

I possess

two

specimens, a male from the "White

Mountains and

afemale from "Washington, D. C.

This species will be very easily recognized

by

its gibbous thorax

and

thetotal absence ofa stigma.

One

of

my

specimens hasthe discal cell closed, the other

open

; thus I

am

iu doubts,

what

isthe rule

and what

the exception.

IS.

D. rara,

n.sp. 9^•

—

Brunnea,capiteantennisquenigris; alisapud costam maculis tribusfuscis, quarts,ad.apicem minore^; veua, auxiliari poneprsefurcseiuitium lougeexteusa.

Brown,head andantenna}black; wings with three brown spots nearthe costa^; afourth,smallerspotneartheapexofthewing; auxiliaryvein prolongedfarbeyondthe originof the prsefurca. Long. corp. 0.23.

Head,

including the

rostrum and

the palpi, black;

antenna

black.

Thorax

pale brownish, with three darker stripes above;

a conspicuous

dark brown

stripe runsfrom the collareacross the pleuri^ towards the

metathorax

;

brown

spots on the sternum,

between

the fore

and

the intermediate coxa3; halteres infuscated_;

abdomen brown, segments

paler at the basis; ovipositor sub- ferruginous; coxiB

and

femora jiale

tawny

; the latter

with

a

brown band

before thetip; knees pale; tibiteand tarsibrownish.

Wings

distinctly infuscated; a

brown

spot (sometimes preceded

by

apale streak) atthe origin ofthe second vein; a smaller one atthetip of the auxiliary vein; a

rounded brown

spot, included

between two

whitish ones, at the tip of the first longitudinal

•76

DirTERA

or

north

AMERICxN..

[part

IV.

vein; a smaller one at the tip of the second longitudinalvein_; cross-veins infuscated, as well as the tips of all the other longi- tudinal veins. Subcostal cross-vein at the tip of the auxiliary vein,

which

is distinctly

beyond

the

middle

of the prtefurca_; marginal cross-vein

very

near the tip of the first longitudinal vein ; secondbasal ^cell alittle shorterthan the first.

Hah. New York

;

two

female specimens.

19. D. defusicla

0.S. % and _J.

—

Fusco-cinerea,thoracevitti3tribus nigro-fuscis,intermedia duplice;pedesnigro-fusci,femoraapicemversus annuloalbido: alseincellulisomnibusseriatimfusco-maculatseetpunc- tatse; veni, auxiliariponeprsefurcjeiuitiummodiceextensa.

Brownisli-gray,thorax withthreebrownstripes,the intermediatedouble;

feetblackisli-brown,femorawitliawhitishringtowardstheapex; wings with brown spots and dots arrangedinrows inallthecells; theaux- iliaryvein is somewhat prolonged beyond the origin of the prsefurca.

Long. Corp. 0.35

—

^0.4.

Syx. Dlcranompadcfunc/a 0.Sacked,Proc. Ac. Nat. Sc. Phil. 1859,p.213.

Head

cinereous, front

and

vertex almost blackin the

middle

_; rostrum, palpi,

and

antenniB fuscous_; joints ofthe flagellum sub- globular,with shortverticils.

Thorax

cinereouswiththree

brown

stripes,theintermediateone divided in

two by

apale longitudinal line ; pleura3 variegated with

brown

; halteres pale with black

knobs

; coxce cinereous, feet

brown,

base of the

femora tawny

;

a very distinct whitish ring ata distance equal to its

own

width,

from

the tip of the femora.

Abdomen

blackish cinereous

;

posterior

margins

of the

segments

paler_; genitals pale.

Wings

with a grayish tinge, spotted with blackish-brown; subcostalcell

infuscated at four intervals; severalspots,

forming

ashort trans- verseband, alongthe central cross-veins; series of small,

round

dots along the middleof the cells; alarger spot atthe tip ofthe seventh longitudinalvein; stigma square.

Hab. Washington, D.

C.;

Trenton

Falls;

Maine

;

Canada.

Ihave often founditalighting

on

rocks

and

stonesover

which

a thin sheet of water

was

running.

The

forceps of this species (Tab. Ill, fig. 1

and

1«) has

more

elongated, slender lobesthanthe typicalDicrayiomyise;

no

rostri- form

horny appendage

is apparent.

The ungues

are large

and have

several notches

on

the

under

side, instead of the teeth,

which

characterize the

Limnobina. The

excision

on

the

under

DICRANOMYIA.

"^"^

Side at the basis of the ^last tarsal joint of the male ^{is distinct,} althousli ^small.

The

following ^species

from

^{California is} not included ⁱⁿ the dichotomicaltable of

page

GO.

OO D. marmoraf ^a

^{0. S. %}.-Cinereo-fusca,thoracevittistribus

^

fuscis; alisciuereo-uebulosis,stigmate quadraugulari,^fusco; femorum apicibus infascatis.

Grayish-brown, thorax with three brown stripes; wings clouded with cinereous; stigma quadrangular,brown;tipof thefemora brown. Long.

corp. ^0.4.

SvN. Dicranomyia marmorala^0.Sackex,Proc. Ac. Nat.^Sc.Phil.1861,p.288.

Rostrum,

^palpi,

and

antenna3

brown;

joints of the ^latter sub- globular, ^verticils short; front

and

vertex ^cinereous, darker in themiddle; thoraxcinereous,

with

threebro^ynstripes_;

abdomen brownish

^{cinereous, posterior}

margins

of the segments pale;

halteres pale^{; feet}yellowish, tips of femora, of the^tibiae,

and

o the tarsi

brown

;

wing,

subcinereous with

some

darker clouds

and some

hyaline

bands and

^{spots; a cloud at}the origin of the^pra3- furca, another,

round

^{one, at its tip;} cross-veins also clouded;

stigma obscure-cinereous,elongated,

quadrangular;

^the

hyalme

spots are arranged ^{in the}following

way

: a ^small,

rounded

one iithe anal angle^{; a}

band running

across the basal portionofthe

two

basal

and

the anal ^cells,

and

ending^{in the} spurious^cell near the posterior

margin

^;aspot near^{thetipof the}seventh lo"gitud.na vein; a large irregularhyaline spaceⁱⁿ the centralportionofthe

Xg

^{inclosing the stigma}

^and

^the

^two

^{cloudsof the pr.furca}

and

^extending

more

orless

towards

the^posterior

margin

^across the ^discal

and

^{the posterior cells; its outline is very}

indefinit

and

it isinterrupted

by

clouded

marks

along the veins; a smal hyaline

mark

^{atthetipofthe wing,in the} submarginal^cell.

1

^e

tip ofthe auxiliary vein

almost

corresponds to the origin of the

J^furca-

^the subcostal cross-vein ^is a short distance before^it.

tip; the ^{discal cell is} present ^(closed),

and

the great^cross-vein

corresponds ^{to itsbase.} _,, . .

„\

_Tbi«

Hab.

^California;

two male

specimens (Mr.

A.

^{Agassiz). Ihi.}

species ^is relatedto

D. humidicola

^{0. S.}