THE OVIPOSITOR OF ORTHOPTERA

42 SMITHSONIAN MISCELLANEOUS 89

V. THE OVIPOSITOR OF ORTHOPTERA

NO. 8 INSECT

ABDOMEN —

SNODGRASS 47 Suhgcnital plate.

— The

exposed sternal plate beneath the genital apparatus; primarily the eighthabdominal sternum, but theseventh

when

the latter underlies

and

conceals the reduced eighth sternum, or the ninth sternum

when

the vaginal openingis transferredto the ninthsegment.

Vagina (Vag).

— The

^genital

chamber when

^the latter takes on ^a pouchlike or tubular

form

withanarrowedposterioropening;in

some

insects extended into the ninth segment to open on or behind the ninth sternum.

Ostium

vaginae, or vulva (Vul).

— The

external opening of the copulatory pouch or vagina, on either the eighth or the ninth ab- dominal segment, serving usually both for copulation and for the discharge of the eggs.

Bursacopulatrix.

— ^Any

cavity of the femaleserving for the recep- tion of themale organ of copulation;usually thegenital

chamber

or itsderivative, thevagina;inmost Lepidoptera adiverticulum of the genital

chamber

invagination on the eighth abdominal segment.

48

SMITHSONIAN MISCELLANEOUS

COLLECTIONS VOL. 89 superieures, inferieures and internes.

The

ventral pair are the ^first valvulae, as designatedinthe present paper, the inner pair thesecond valvulae,

and

the dorsal pair the third valvulae. In Gryllidae and Acrididae the inner, or second, valvulae are rudimentary, and the functional part of the ovipositor thus consists of only

two

pairs of valvulae. Hence,^it must be observedthat the four-valve ovipositor of these insects differs

from

the four-valve ovipositor of Thysanura, Hemiptera, and

Hymenoptera

inthat the shaftisformed of the^first

and

third valvulae, while inthe latter groups it consists of thefirst

and secondvalvulae.

The

firstvalvifers arealwaysdisplacedposteri- orlyintheOrthoptera andcloselyassociatedwiththeninthsegment the secondvalvifers areneverdistinctlydifferentiated

from

the third valvulae.

^Eppfc

-Cer

VlllStn iVlf iVl

Fig. 12."

—

Female nymph ofScudderia.

Dorso-pleurallineofabdomenmarked byafold(a-a);ovipositor with small basivalvular sclerite {hv) atbaseoffirstvalvula (iF/);epiproct (Eppt) par- tiallysurrounding baseofcercus (Ccr).

The

six-valve type of ovipositor is typically developed in Gryllo- blattidaeandTettigoniidae,but the basal parts of theorganaresome-

what weak

inthesefamilies,andinstructure they are scarcely repre- sentative of that of the highly perfected basal

mechanism

of theovi- positor of Gryllidae.

A

^{brief study of atypical form, suchasScud-}

deria,however, willserve asanintroductiontothe

more

detailedde- scriptionof Gryllustofollow.

The abdomen

ofScudderia (fig. 12) presents awide

membranous

area on each side in which ^{the spiracles} are located.

A

prominent groovetraversing thelowerpartof the

membrane marks

the dorso- pleuralline{a-a),whichposteriorlyextendsabovethe basalplatesof the ovipositor.

The

spiracles lie in the laterodorsal, or paratergal, region of the

membrane

{patg) above the dorso-pleural line.

The

eighth, ninth, and tenth terga are distinct, and the epiproct {Eppt)

is well developed.

The

eighth sternum (VlllStn) forms a small

1

NO. b INSECT

ABDOMEN

SNODGRASS 49 subgenital plate underlapping the base of the ovipositor.

The

first valvifers {iVlf) aredisplacedposteriorly,andarethusentirelysepa- rated

from

thetergumof the eighthsegment,thoughthey arein closer associationwiththe eighth sternum.

The

broadovipositorshowsonly thefirstandthirdvalvulae externally {iVl,3VI),thesecondvalvulae being concealedbetween theouterblades.

The

mature ovipositor of Scuddcria is strongly upcurved, andits freemarginsare toothed (fig. 13C).

The

mechanicalrelationsof the parts of the organto oneanothercanbe studied only in fresh speci- mens, orin specimens preserved in liquid; the parts are best seen

when

the entire ovipositor is

removed from

the body.

Each

of the first, or ventral, valvulae (iVl) is attached to a small, oval lateral plate atthebase of the ovipositor (iVlf), which isthe firstvalvifer ("pileolus "ofChopard, _1920).

The

^{firstvalvifer}anditsvalvula are continuous, but they areflexibleon eachotherby reasonof the nar- rowness of their union (c).

The

upper end of the valvifer is con- nected, alsobyaflexibleunion _(&), withthe basal part of thebroad third, or dorsal, valvula (sVl), the side of which it overlaps ven- trally.

From

anangleontheanteriormarginof the^firstvalviferthere projects internally a strong

apodeme

(e), on which muscles areat- tached. If thefirstvalviferis revolved

upward

onits flexibledorsal attachment (b), the ventral valvula is retracted. In

some

of the Tettigoniidae the proximal part of the firstvalvula is

more

or less distinctly difterentiated as a basal sclerite, or basivalvula,

shown

in the

nymph

of Scudderia (fig. 12, hv).

Each

of thedorsal,orthird,valvulaeofScudderia (fig. 13 C, 3VI)

is

somewhat

thickenedatitsbase

where

thefirstvalviferisattached, there being differentiated here an area {2Vlf) that evidently corre- sponds withthesecondvalviferofanovipositorhavinga

more

typical structure (figs. 10 C, 31B), inwhich each limb baseelement of the ninth segmentbecomes divided into a valvifer {2Vlf)

and

a distal lobe {3VI).

The

muscles inserted on this basal part of the dorsal valvula in Scudderia and other tettigoniids are those of the second valvifer in other insects.

The

area in question is sometimes called the^"basivalvula^" of the dorsal valvula,but the termisunnecessary andmisleading since the area so designateddoes notcorrespondmor- phologically with the basivalvula of the ventral valvula.

A

strong

apodeme

(fig. 13 C, g) projects

from

the anterior margin of the valvifer area. This

apodeme

is the superior apophysis of

Walker

(1919).

The

dorsal and ventral valvulae are ratherweakly connected with each otherin Scudderia, but inthe Tettigoniidae andGryllidae gen-