148 DIPTERA OF NORTH AMERICA. [PART IV

been introduced

by Meigen

as early as 1803 (Illiger''s

Magazin,

Vol.

YI). In

the first

volume

of his principal

work

(Systemat.

Beschr. etc. Yol. I, p. 108)

he mentions among

the characters of the

genus

that

"the wings

are pubescent along the veins only." It

must

notbe overlooked, however, that at the time of thepublication of this

volume

he

had

not seen

any

ofthe species

with

the

wings

hairy

on

the

whole

surface.

When

he obtained such a species(E. varia, Yol.

YI,

p. 237)

he

included it in the

same

genus. Since

Meigen, Erioptera

has been understood

by

later authors (Macquart,Zetterstedt, Staeger,

and

"Walker)inthe

same

sense, that is, as including the species with the

wings

pubescent

on

the

whole

surface, as well as those pubescent along the veinsonly.

In

1833 Mr.

Curtis(British

Entomol.

444)

proposed

the

adop-

tion of the

genus Molophilus

fora species

which

he described as

Molophilus

brevipennis, but

which

later English entomologists

unanimously

considered as

synonymous

with

E.

atra Meig.'

The

characters

upon which

this

genus was

established (modified shape of

abdomen and

thorax, smallsize ofthewings,

and

large size of the

male

forceps)

do not

warrantits retention inthe sense of the author, butthe

name Molophilus may be

well retained for the

subgenus

to

which E.

atra belongs.

In 1848 Mr.

Rossi (System. Verz. etc. p. 12)

proposed

the generic

name

of Cheilotrichiaforthe

European

species

having

a discal cell (E.

imhuta and E.

cinerascens),

however

without nearerdefining this

new

genus.

In 1860 Mr.

Kolenati

(Wien. Entom.

Monatschr. Yol.

lY) adopted

the

genus Rhypholophus

for a

new

species, discovered

by him

in Austria. This

name

has

been

retained inthe present volume, but in a

more extended

sense.

' The

synonymy

of

M.

brevipennis with E. atra M., admitted by all English authors (compare Westwood, Walker, etc.), is probably based upon a comparisonof original specimens. If

we

holdontoMr. Curtis's description only,this

synonymy may

appeardoubtful.

He

(^Brit.Entom.

557) mentions both E. atra andE, viurina

among

the species found in England, although in the same article he speaks of

M.

brevipennis as a distinct species. In the description of this specieshe saysthatthewings are"straw-colored" at the basis; from thefact that the author,having bothsexes beforehim, doesnot notice the difference in the lengthoftheir wings, onewouldinferthattheyare short inboth,andthisisnotthe case with E.atra, etc.

ERIOPTERA,

149 In

the

same

year

Mr. Rondani

(Prodr. DipterologiseItalicse, Vol. I)proposed a seriesof

new

generic

names

for certain

groups

of the

genus

Erioptera.

They have

already

been enumerated above

(p. 12), but

among

that

number

Ilisia alone, with

Erio2>

tera

maculala M.

for type, has

been

described (ilfws. Canestr.

Ill, p. 91, 1865).

The

description of the others is to be ex- pected in the

volume

of

Mr.

Rondani's

work which

willtreat of the Tipulidse,

and

which, as far as I

am

aware, has not yet appeared. This circumstance, as well as

my

limited

knowledge

of the

European

Eriopterse, prevent

me from

entering in a detailedexamination of this distribution.

In

1863 Mr. Lioy

{AttiInst. VeneL,

3d

series. Vol.

IX,

p.224) proposed the genus

Platytoma

(with

E.

cinerascens

M.

fortype) for the EriojJterae with a discal cell

and

with an incrassated second antennaljoint.

Dr. Schiner

(Wiener

Eyitomol. Monatschr. Vol.

VII,

1863,

and Fauna

Austriaca, Diptera, Vol. II, 1864) divided the

genus Erioptera

(in the broadest sense)in four genera,

which may

be tabulatedthus^:

—

I.

Wings

pubescentonthewholesurface.

1.

A

^discalcell

Rhypholophus.

2.

No

discal cell, and anterior branch of the

fourth veinforked

....

^Dasyptera.

II.

Wings

pubescentalong the veins only.

1. Thefork ofthe fourth longitiidinal rein,and withit,the great cross-vein, areintheir usual position^; the posterior branchof

thefourthlongitudinalveinisforked . Trichosticha.

2. Theforkofthe fourthlongitudinalveinand with^it,the great cross-vein, are

much

nearerto the root ofthewingthanthe

smallcross-vein Erioptera.

Under

the

head

ofthe

genus Bhypholophus

(comp. p. 139) I

have shown why

Dr. Schiner's subdivision of the species of Sect.

I ("

wings

pubescent

on

the

whole

surface") cannot be retained forthe present. Inthe

same way,

the subdivision of Section II

("wings

pubescent along the veinsonly") is inapplicable to the

North American

species.

The

definition of IVichosticha, as given

by

the author, excludes

two

JSTorth

American

species (E.

caloptera

and

parva),

and perhaps some European

_{ones (E.}tsenio-

150

mPTERA

^OF

NORTH AMERICA. [PART

IV.

nota Zett. Dipt. Scand.

X,

p.

3181

?)

which have

the anterior

branch

ofthe fourth veinforked.

Whether we

enlarge the genus, so as to admitthese species, or

whether we

leave ^itintheaccep- tation of the

Fauna

Austriaca, Trichosticha will contain very heterogeneous elements.

The genus

Erioptera, inDr. Schiner's limited acceptation, is a natural group,

which

I

have

retained below. Itistoberegretted,however, thatthe authortransferred to this

group

the

name

of Erioptera,

which

belongs

much more

legitimately to his

genus

Trichosticha, as containing Meigeu's

most numerous and

typicalspecies.*

In

the Proc.

Acad.

Nat. Sci. Philad.

1859

(p. 225), I

have

indicatedthe principal

groups

of the

North American

Eriopterse.

They

are substantially the

same

asthose

which have been more

fullydefinedin thepresentpublication. IfI have retained

them

inthe position of

groups

orsubgenera,itisbecause,in

my

opinion, the characters

which

allthese species possess in

common

^consti-

tute

between them

a link of afiinity

more

important than the structural differences

which some

of

them show. Even

the-

genus Rhypholophus,

as defined above, proves

by

the position of its subcostal cross-vein, the

manner

in

which

the second longitudinal vein originates, and, in

some

species,

by

the arcuated course of the seventh longitudinal vein, a strong affinity to the

genus Erioptera

in its presentdefinition. If I

have adopted

these

two

genera,it isbecause the differencein thepubescenceof the

wings

of bothaffords a

ground

of subdivision as simple as easily appli- cable to all thespecies at present

known. But

^it remainsto be

shown

yet,

whether

the difference in this characteris indicative of

some

corresponding modifications inother organs.

Another

potent reasonfornotfurther subdividing the

genus Erioptera

in

my

case was,

my

unacquaintance with the

European

species, the rather small

number

of the

North American

ones,

and

the

com-

paratively large

number

ofsubdivisions

which

theyrequire.

For

allthese reasons I

have

preferred to indicate thenaturalaffinities existing

between

the

North American

Eriopterse,

and

to distri- bute

them

in

groups

accordingly, leaving these

groups

in the position of subgenera.

' It

may

besaidinfavorofDr. Schiner'snomenclature,thatMeigen,in his earlierwork (Klassljicaiion, etc. 1804),has figuredErioptera

aUa

as if it was the type ofthe genus. In his principal work the species art}

arrangedin adifferentorder,andthisfigureisnotreproducedatall.

ERIOPTERA, 151

The North American

species,containedinthe

genus

Erioptera, asdefinedabove,

may

be distributed into thefollowing groups^:

—

A. The prsefurca ends in the second submarginal cell, which is longer thanthefirst;the innerendofthe discalcell (or,

when

itisopen, of thecellwithwhich it coalesces) isonthesame linewithtlie

smallcross-vein (Tab.I, fig.16, 17,18).

1. Theposteriorbranchofthe fourth longitudinal vein isforked (in otherwords,

when

the discalcellisopen,it coalesces with the second posterior cell;

when

it is closed,theinnerend ofthe third posterior cell is nearer the basis of tha wing than theinnerendofthe second).

a. Theseventh longitudinalvein is arcuated (converging to-

wardstliesixth) in suchamanner,that the axillary cellisbroaderinthemiddle than near themarginof thewing (Tab.I,fig.16)^: subgenusErioptera.

The

six species of this

subgenus

{E. chlorophylla, straminea, vespertina, septemtrionis,

chrysocoma,

villosa)

form

averynatural

group

; theirvenationisexactly the

same

;their discalcellisopen, eoalescent with the second posterior cell; their third posterior cellis ratherlong; their

male

forceps

seems

to bebuilt

upon

the

same

plan,

and

consistsof

two

basal j^ieces,bearing several

horny

branches each

(compare

Tab.

IV,

^fig. 20,the forceps of

^.

vesper- tina); their

wings

are immaculate,theirfeet without well-marked bands.

Although

the

above named

six

North American

species

have

the discal cellopen, the

mere

factofits being closed

would

not prevent a

new

species from being included in this group, if

the

agreement

inthe othercharacters

was

sufficient.

The

present

group

almost answers to Dr. Schiner's

genus

Trichosticha; but

it

seems

to

me

that

Erioptera

isa

more

appropriate

name

for it,

asitwill probablyinclude the majorityof the species, as well as the

most

typical forms, of the

genus Erioptera

in the sense of Meigen'sprincipal work.

b. Theseventhlongitudinalveinisstraight,diverging fromthe sixth; hence the axillarycell is

much

broader near themarginofthewingthaninthemiddle; discalcell closed.

* Thefork of the posteriorbranchofthe fourth longitudi- nal vein (containing the third posteriorcell) has the usualstructure,thatis,consistsof twogently arcuated branches (Tab. I, fig. 17)^: subgenus

Acyphona.