OUR PRESENT KNOWLEDGE OF NORTH AMERICAN

OF WASHINGTON. 13

colony, ^or*sleeping place,

was

tenanted

by some

eight or ten different _species.

Although he

^{noticed a}

few

9 $,

most

of the specimens observed

were

cT cT.

Small

bees

were found

inclosed blossomsofthelace flower, or wildcarrot

(Daucus

carota)^,while

bumble

bees rested

under

_{the edges}of certain flowers.

Wasps

belonging ^to the

genus Ammophila

^held

^on

^to grass

stems by

^{their mandibles, the}

body ^extended

straight

and _wings

closely folded.

Some

other _species usetheir

mandibles

in the

same _{way, but} Ammophila

^is the only ^insect which, ⁱⁿ

some

cases, uses its

mandibles

exclusively for ^this purpose, thelegs not touching the stem.

Mr.

Banks

referred to his recent visit to the

Museum

of

Comparative Zoology

^at

Cambridge,

^Mass.,

where he made an examination

^of

Hagen's

collection of Neuropteroid^insects

and Emer

ton's collection of _spiders.

Some

of Keyserling's types of spiders, also, are depositedⁱⁿ the

Museum. He

stated that

Hagen's

^{collection has not}

been

_rearranged

but

is

kept

^intact just as

Hagen

^{left it. This Mr.}

Banks

considered

most com- mendable and

a_policy

which

should

be more

generally followed.

Mr. Caudell

mentioned

instances

which have come under

hisobservationofthe

mating

of different species of Melanoplus, Sckistocerca,

and

other Orthoptera.

The Morse

collection of Acrididge,

he

_stated, contains a fine seriesof intergrades.

The

subject of hybridization

was

discussed

by

^Messrs. Piper

and

Gill, the latter statingthat so-called

new

_genera in fishes

have been based upon

hybrids

between

different genera.

Dr.

Dyar

^{read the} following paper:

OUR PRESENT KNOWLEDGE OF NORTH AMERICAN CORETHRID LARVAE.

BY HARRISON

G.

DYAR.

Having

discussed, in conversation with Mr. Coquillett, the relationships ofthe Diptera ^{allied to} the_Culicidae, it

seemed

to usa

more

natural

arrangement

^to separate the^truemosquitoes into a distinct family

on

the character of the presence ^of the proboscis,

and remove

the non-biting forms, the old Coreth-

ringe, placing

them

with the Dixidae as a second _family,

under

the

name

Corethridse. In thelarvae of this

group

^the

mouth

brushes are

somewhat

_developed,

and

in other characters they

approach

^{the true} mosquitoes.

14 ENTOMOLOGICAL SOCIETY

Dixa

is the

most

generalized

form and

is a surface _feeder, taking small vegetableparticles

by

the rapid

motion

ofits

mouth

parts.

The

air tubeis well developed,

but

_sessile,

and

there are false

abdominal

feet to assist the larva in ascending the

water

film at the margin, ^{as is its habit.}

From Dixa can be

derived not only ^all the other Corethridae,

but

the Culicidae as well. Anopheles, ^for example, ^is

very

^{close to}

Dixa

in

many

characters.

Except

Dixa, ^all the Corethridae are predaceous, feeding largely

on

the larvae of the true mosquitoes.

Next

to

Dixa comes

Eucorethra, withitsairtubestill sessile,

but

the

mouth

parts modified for its predaceous ^{habits. It is still} nearly a surface feeder, lying ^flatly in the water. Corethrella isa fur-

FIG.2. StructuraldetailsofNorth AmericanCorethridlarvae: a, ciliated plateofairtubein

Dixarecens; b,analsegment^ofDi.ra recens;c,thesameofD.centralis; d, leaf-likeappen- dage^ofSayomyia americann^; e,the s.^me ofS.trivittata;f, thesameofS.knabi

ther specialization of ^this type, the air tube

having become

elongated, allowing the larva ^{to sink} lower inthe _water, while the_peculiarrapacious antennae^are

remarkably

adapted.

Corethra

shows

a

development

^{in a differentdirection.}

The

air tube is elongated,

but

apparently could not

be adapted

^to the requirements ^of the _{larva, as} it

became

_necessaryfor itto sink deeper

and

_deeperin the _{water, so} ithas

begun

^to

be

dis- used.

The

horizontal position^isstill

maintained by

^theforma-

tion of air bladders,

one

_{pair in} the_thorax, a second near the

end

of the

abdomen. These

are enlargements ^of the tracheal tubes

and

are joined

by them

^{to theair tube. It}

^{would seem}

that this fortunate

arrangement

supplied the larva with ^air- reservoirs, sothat it isable to stay long

below

the surface

and

frequent the depths

where

itfindsitssubsistence.

OF WASHINGTON. 15

Sayomyia

^has

accomplished

^{a still}further specializationalong theselines. Ithas dispensed

with

theairtube_entirely

and

the trunks of the trachealtubesas_well, whileitfloats like atrans- parent ghost

deep

^inthepool, carrying^itsfoursacs ofair

which

are

now

neverconnected with the airabove.

We

suppose that theair in these sacs^isreplenished

by

^diffusion

through

^the

body

walls

from

the air dissolved in the water;

but

the character appears ^to us asa

very remarkable one which would

^not

have been

antecedently

thought

possible.

The

Corethridae, as here _limited,include 23species described

from North America. Of

these

we know

thelarvae of 15

more

or less completely.

There

are

no unknown

_genera,

and

it is

probable that the

unknown

_{species of}

Dixa and Sayomyia

^are

similarto the

known

^ones.

Indeed some

^ofthe_{species of}

Dixa may ^be synonymous

^;

^{but on}

^the other hand, there are prob- ably a

number

of

forms

^to

be

discovered.

The

subject has

been very

^little

worked.

The

_{following synoptic}table will separate the

known

larvae^:

1. Air tube _present 2

Airtubeabsent, larvaeaquatic.^. 7

2. Airtubesessile,larvae atsurfaceofwater ₃

Airtubeelongate, larvaebelowsurfaceofwater 6

3.

Abdomen

withfalse feet

; antennaenot_longerthanothermouth_{parts 4}

Abdomen

withoutfalse feet; antennae longanddirectedforward

Eucorethraunderwoodi

4. Ciliated plates of theairtube without a projecting triangular^hairless

apex Dixaclavula^l

These_plateswith such an apex(fig. 2,a) 5 5. Anal segment finely haired, the hairs shorterthan the stout terminal

cone (fig. 2, 6) Dixa recens

Anal segmentcoarselyhaired, the hairslongerthanthe smallterminal

cone (fig. 2,c) Dixacentralis

6. Antennae moving ^{in a horizontal} plane; ^larvae flattened dorso-ven-

trally Corethrella brakeleyi

Antennae moving^{in avertical} plane; larvae subcylindrical,

fCorethra_cinctipes^"*

J Corethralintneri

I Corethravelutina {^Corethrakarnerensis

1 modesta Joh. According ^toMr. Johannsen's figure (Bull. 68, N. Y.

State Mus., pi.48, figs. 5and7, 1903). ^I havenot myself seen the^larva.

The_{projectingapexbelongs}tothe outer sheathofthe plateandit

may

^not

beshowninJohannsen'sfigure.

21

am

unabletodistinguish CorethracinctipesCoq.and C. velutinaRuthe.

Thelatter

may

^{not be the} European ^{form, but C.} karnerensis Felt orC.

lintneri Felt, which I

am

likewiseunableto distinguish.

16 ENTOMOLOGICAL SOCIETY

7. Leaf-likeappendages^beforethemouthasbroadas long, serrateonthe

j _,(. x (Sayomyia^americanal end

&%

^2'

^

...

\Sayomyia^hudsoni These appendagesnarrow,

much

_longerthanwide ... 8 8. These appendages^{serrate(fig. ,..)..}

These appendages smooth, ^{at least}outwardly, long pointed ^{(fig. 2,/)} (Sayomyia sp*

\Sayomyiarotundifolia

Mr. Currie presented the following

paper

^:

DRAGONFLIES FROM THE KOOTENAY DISTRICT OF BRITISH COLUMBIA.

BY ROLLA

P.

CURRIE.

About

_{a ye?r}

_ago

the writer

gave

the Society a general ^ac-

count

of the

Kootenay

District of British

Columbia and

of the three

months

_spentthere

by

^Dr. Dyar, Mr. Caudell

and

himself in the

study and

collection ofinsects.

The

dragonflies consti- tutea

group

ⁱⁿ

which he

is especially interested,

but

the effort to collect a

good

^series of insects in all Orders prevented ^his devoting ^as

much

attention to the

Odonata

as

he might have

wished. Nevertheless, the collection of

Kootenay

dragonflies

1Mr. Johannsen separates the American form of plumicornis under a

new

name

becausethe four spines^oftheantennae are equalin length. But Mr.

Knab

has called

my

attention toWeismann's article _(Zeits. fiir wis- sensch. _Zool.,xvi, 1866) wherethe spines areshownofequal lengthⁱⁿthe European ^form. But Dr. Felt repeats the statement of the difference (N.Y. State Mus.,Bull. 79, 370, 1904) and_figuresthe leaf-likeappendages ofthetwoforms,which appearslightly different. ^Itherefore provisionally use Mr.Johannsen's name. ^S. hudsoni Felt does notseemtodifferinany tangiblemanner.

2Mr.Johannsen ^cites

my

figure of this speciesas indicatingbuttwohairs onthe anal segment. The_figureisdrawnasifofonesideonly; there are in fact four _hairs, two on each side. To _judge by ^Dr. Felt's figures, S.

albipesJoh.^differsinthe smallerdevelopment^{oftheserrations}on_{the edges} of the appendages.

3This

may

^{bethe larva of 5.} punctipennis Sayor 5. rotundifolia Felt.

The_specimenwascollected by^Mr.F.

Knab

at Springfield,Mass. Dr. Felt saysof rotundifoliathattheleaf-likeappendages have^{severalrather}large irregularteethatthebaseofthe long pointedprocess. Intheformbefore

me

^thereisscarcely a trace^ofanirregularityanywhere, andit is,therefore, probably^adistinct species. ^It

may

^{becalled Sayomyiaknabi,newspecies.}