38 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 94

271

Ap

274- 263 256\

-— ^iVl

Fig. I/.

—

The ovipositor and its muscles. Dissosteira Carolina.

A,ovipositorandmuscles,leftside. B,mediansection ofovipositorshowing mesal view of rightvalvulae and muscles. C, dorsal viewof ovipositor and muscles. D, ventral view of second and third valvulae, with apodemes, and musclesofanteriorintervalvula. E, ventralviewofventralvalvulae,dorsalwall of genitalchamberwith spermathecal aperture, andspermatheca.

a, lateral basivalvular sclerite; aiv, anterior intervalvula; Ap, apodeme of ovipositor; b, c,first andsecond ventral basivalvular sclerites; e, _f,apodeme and apodemal sclerite of anterior intervalvula; g, base of third valvula; h, ventral lip of apodemal invagination; i, articular process on ramus of third valvula; IXT, lateral parts of ninth tergum; piv,posterior intervalvula; ra, ramus of thirdvalvula; Spr, spermathecal aperture; Spt,spermatheca; SptD, spermathecal duct; iVl,2VI,3VI,first, second, andthirdvalvulae.

NO. 6

GRASSHOPPER ABDOMEN

SNODGRASS 39 end of the

abdomen

(fig. i) beyond the eighth sternum (VlllStn)

from

beneath the lobes of the eleventh segment {Eppt, Papt), and thusmight appeartobelongtothe ninthandtenth segments;thefirst valvulae, however, are developedin the

nymph from

the eighth seg- ment, immediately behind the eighth sternum (fig. 22 A, C, iVl)

,

andthesecondandthird valvulae

from

theninthsegment (A,C,D).

In the adult several basivalvularsclerites are differentiated

from

the bases of the firstvalvulae (figs, i, 17A, a,b, c),v^hich,thoughpar- tiallyoverlappedbythe eighth sternum, are entirelyseparated from thelatterby aninflectionof the poststernal

membrane

that formsthe femalegenitalchamber.

Between

thebases of the dorsal valvulae are anteriorandposterior intervalvularsclerites (fig. 17 B,aiv, piv);and a pair of large

apodemes

projects forward in the body cavity

from

theanglesbetweenthebases of the dorsalandventral valvulae (A,B, D,

Ap). An

important accessory of the acridid ovipositoris theegg guide, amedianprocess of the eighthsternum (fig.20 A,eg).

The

^first, or ventral, valvulae of Dissosteira Carolina ^(fig. 17A, B, E, IVI) are

somewhat

elongate lobes, flattened

from

side to side, ending each ina decurvedpoint. Proximally they are unitedbythe

membranous

integument between ^theirbases,

and

theirventral walls arecontinuedintothedorsalwall of the genital

chamber

(fig. 20

A).

Each

first valvulais differentiatedinto a strongly sclerotic terminal lobe (fig. 17A, iVl),

and

intoa basal part containing a large^lateral basivalvularsclerite (a) and

two narrow

ventralsclerites {b, c).

The

upper surface of the terminal lobe (B) isproduced proximally asan elongateplate, orramus,attheend ofwhichis awide transverse de- pression that fitsclosely

upon

aprominent abutment

from

the under surface of the basal

ramus

of thecorrespondingthird valvula (D,i).

Proximal to this articulation the dorsal wall of the ventral valvula is

membranous

andshortlyends atthe ventral lipof thehollow base of thelateral

apodeme

(Ap).

The

lateralbasivalvularscleriteof the firstvalvula (A,a) is aprominent plateexposed onthe side of the

abdomen

behind the eighth sternum (fig. i).

The

posterior ventral sclerite (fig. 17A, B, b) is ordinarily partly exposed behind the eighthsternum, but the anterior ventral sclerite (c) is concealedin the dorsalwall of thegenital

chamber

(fig. 20

A), where

itflanks a medianchannel containing the spermathecal aperture (fig. 17E).

The

third, or dorsal, valvulae of Dissosteira (fig. 17A, B, 3VI) resemblethe ventral valvulaeingeneral form,except thattheirpoints areturnedupward,but they are largerandstrongerthanthe ventral valvulae,andtheyhave nobasivalvularsclerites. Theirdorsalsurfaces proximaltotheupcurvedpointsarebroad

and

flat.

The

undersurface

40 SMITHSONIAN' MISCIlLLANEOUS COr,LF.CTIONS VOL. 94 ofeach dorsal valvulaisprolongedanteriorlyina strong ventral

ramus

(D,ra), theexpandedbase ofwhich (g) ^isfirmlyhingedtothe dorsal lip of theexposedbase (li) of the lateral

apodeme

of the

same

side.

The

apodemalbases,therefore, are the fulcral points for the

move-

mentsof thedorsal valvulae.

The

ventral valvulae,onthe other hand, have their fulcra of

movement

on the stronglyprotruding articular ridges (/) on thebases of the dorsal valvulae.

The

dorsal valvulae are unitedbetweentheirbasesbya

membranous

integumentcontaining the anterior intervalvula (D, aiv), the bases of the secondvalvulae {2VI), andtheposterior intervalvula (B, C, piv).

The

second, or intermediate, valvulae (fig. 17A. B, D, 2]!) are short lobes projecting

from

the

membrane

between the ventral rami of the dorsal valvulae.

The two

areadnate mesally formostof their length,buttheir sclerotic lateralandterminal parts

form

free lobes en- closing a trough-like depressionbetween

them

(D).

The

united bases of thesecondvalvulae are supported on amedian process of the an- terior intervalvula (aiv).

The

intervalvulae are small scleriteslyingbetween^thebases of the dorsal valvulae, where, because of the position of the latter, they

become

dorsalandventralrelativetoeachother.

The

ventral anterior intervalvula (fig. 17D,aiv) isa transversescleritebridging the space between the anteriorends of the ventral rami of the third valvulae,

and

giving support by a medianprocess to the united bases of the second valvulae. Just before the transverse sclerite is a small, oval, mediansclerite (/) bearing a short slender

apodeme

(e) on whichare attached themusclesof the anteriorintervalvula.

The

posteriorinter- valvulais a smallhexagonal plate lyingdorsallybetweenthebases of thethirdvalvulae (B, C, piv).

A

characteristicfeature of the acridid ovipositoris thepresence of the pair of long, flat, lateral

apodemes

(fig. 17D,

Ap)

extending forward from theanglesbetweenthebases of the dorsal andventral valvulae. These

apodemes

are well developed also inTetrigidae and Tridactylidae,but theyhaveno apparent homologues intheovipositor of other insects.

They

give attachment to the levator anddepressor musclesof the valvulae,tothemuscles of the posteriorintervalvulae, andtothe ventraldilatorsof therectum, while the proctractormuscles of the ovipositor are insertedontheiranterior ends.

The

stalk of each

apodeme

is hollow, andits base appears asthe strongly sclerotic lips of a transverse cleft in the angle between the bases of the dorsal andventral valvulae,where, asalready observed, the ventral

ramus

of the dorsal valvulais hingedto thedorsallip of theapodemalinvagination. Itmightbe supposed, therefore, that the

NO. 6

GRASSHOPPER ABDOMEN

SXODGRASS 4I