123 



Overlælien (Fig. 11. i), som (lainier den umiildel- 

 liare Fortsættelse af Hovedets ventrale Fladr-, er af 

 betydelig Storrelse og rækker ind mellem Basis af 

 Lste, tildels eiidogsaa 2det Fod]iar. Den liar For- 

 men af en atiang. noget sammentr\kt Laji, der i sit 

 ydre Parti danner en noget nedadhoiet, rundtom 

 fint cilieret oval Lamelle, nden nogen saadan ten- 

 takelfi.irmig Fortsats som lios Limuadiu. Overlæben 

 kan loffes af fra Munddelene ved et Par tynde 

 Muskler, der fra Hovedets Integnment passerer til 

 dens Basis. I dens Indre sees. som hos Linmadia. 

 tiere celleagtige Legemer og et Antal af tværgaaende 

 Muskler, som virker paa dens ovre blode og rende- 

 formigt fordybede Flade. 



Kindbakkerne (Fig. 4, Fig. 11, M) ligger, som 

 ho.? Linmadia. i Form af 2 boileformige Legemer til 

 hver Side ])aa Urændsen mellem Hovedet og Nakke- 

 segmentet. l)eres ovre tilspidsede Ende er articu- 

 leret til et fortykket Parti af Integumentet ved 

 Enderne af den mellem begge de ovennævnte Dele 

 gaaende Tværsutur, medens deres nedre, stærkt ind- 

 boiede Ender modes paa Undersiden ved Mundaab- 

 ningen. Tyggedelen er stærkt, na^sten oxeformigt 

 udvidet, og viser en noget tilskjærpet Kant delt i 

 en Række stumpe Tænder, hvoraf den yderste er 

 stør.st. I sin Bevæbning skiller altsaa Kindbakkerne 

 hos nærværende Form .sig meget væsentligt fra 

 samme hos de ovrige bivalve Pliyllopoder og viser 

 en Tilnærmelse til den for Apodiderne characteristiske 

 Bygning. 



Forste Par Kjæver (Fig. 4, 11. ;;; *, Fig. o'), be- 

 staar, som hos Lrninadia, af en tykkere Basaldel og 

 en bevægelig Endeplade; men denne sidste er her 

 betydelig smalere, leformigt indadkrummet, og kun 

 forsynet med et liegrændset Antal af stærke, iiled- 

 dede Borster. Langs den indre Kant af Pladen tæl- 

 ler man 8 saadanne Borster, noget tiltagende i 

 Længde iidad og tint cilierede i den ene Kant (se 

 Fig. 5 a). Ved Spidsen af Pladen er fæstet 3 be- 

 tydelig kortere Borster. der er jiigtVirmige og grovt 

 tandede i begge Kanter (se Fig. 5 b). I den ydre 

 Kant har Pladen ved Basis en meget fin Ciliering. 



Andet Par Kjæver (Fig. 4, 11, ni', Fig. 'i), der 

 ikke er bemærkede af (Irube, er meget rudimentære, 

 kun forestillende et Par sim] ile. noget hjertefcrmige 

 Lameller af en delikat membranos Beskaftenhed, i 

 hvilken Henseende de nærmest synes at svare til 

 den ydre Udvidning (Palpe) af disse Kjæver hos 

 Lepidurns. Deres Beliggenhed, temmelig langt fjer- 

 nede fra Midtlinien (se Fig. 4), taler ogsaa for en 

 saadan Tydning, hvorved altsaa den egentlige Tygge- 

 del maa antages at være ganske oblitereret. Lamel- 



the .scape, ln the outer part of the latter, other 

 muscles are visible, which act ujioii each of the 

 rami. 



The labi'um (Hg. 11, L). which forms an imme- 

 diate continuation of the ventral surface of the 

 head, is of considerable size, and extends between 

 the bases of the 1st, and partly also of the 2nd 

 pair of legs. It has the form of an oblong, ra- 

 ther compressed lobe, whose outer part forms a 

 somewhat downward-curved, oval lamella, finely 

 ciliated all round, and without any such tentacular 

 jn'ojection as in Linmadia. The labrum can be 

 raised from the oral ])arts by a pair of thin muscles 

 passing to its base from the integument of the head. 

 In its interior may he seen, as in Lininadia, several 

 cellular bodies, and a number of transverse mus- 

 cle.s, acting upon its upper soft and grooved si^rface. 



The mandibles (fig. 4, fig. 11, 31) lie, as in Lini- 

 vadia. in the shape of 2 bow-shaped bodies, one on 

 each side, at the Ijoundary between the head and 

 the cervical segment. Their upjier pointed end is 

 articulated to a thickened part of the integument, 

 at the ends of the transverse suture which runs 

 between the two parts jttst named; while their 

 lower, much incurved ends meet on the iTuder sur- 

 face at the oral ajierture. The masticatory part 

 is strong, and almost securiformly expanded, and 

 exhibits a somewhat sharpened edge, divided into a 

 series of blunt teeth, the outermost of whicli is the 

 largest. Thus, in the matter of equipment, the man- 

 dildes in this form are very essentially distinct 

 from those in the other bivalve Phyllopoda, and 

 show an approach to the structure characteristic of 

 the Apodidff'. 



The 1st pair of maxillæ (figs. 4. 11. m ', fig. 5) 

 consist, as in Linmadia. of a thicker Ijasal part and 

 a movalile tei-minal lamella; but the latter is here 

 considerably narrower, is citrved falciformly inwards, 

 and furnished with only a limited number of strong, 

 unartii-ulated liristles Along the inner edge of the 

 lamella, 8 such In-istles may be counted, somewhat 

 increasing in length outwards, and finely ciliated on 

 one edge (see fig. 5 a). To the point of the lamella 

 are attached 3 considerably shorter bristles, which 

 are spiniform and coarsely dentated on both edges 

 (see fig. ob). At its base the lamella is very fineh' 

 ciliated on the outer margin. 



The second pair of maxillæ (figs. 4, 11, m'\ 

 fig. 6), which have not lieen oliserved by (xrube, 

 are very rudimentar\-, representing only a pair of 

 simple, somewhat cordate lamellæ of a delicate, 

 membranous consistency, in which respect they seem 

 almost to correspond to the outer expansion (pal])) 

 of these maxillæ in Lepidiinis. Their position, at 

 some distance from the median line (see fig. 4). also 

 favours such an interpretation, whereby the true 

 masticatory part nutst be assumed to be (|uite 



