93 



Spor at' tandt'uriuige Freiuspring. Foruden de kraf- 

 tit!,'e Addnc'tormusklei', der fylder Storsteparteii at' 

 den indri.' Hnllied at' Coriius, spes ogsaa en Del 

 andre Muskler at passere til Kindliakkerne, ved 

 Hjælp af hvilke disse kan dreies om sin Axe inden 

 visse Grændser. De stærkeste af disse Rotations- 

 innskler iidspringer fra den dorsale Flade af Nakke- 

 segmentet og convergerer mod Kindbakkernes l)agre 

 Side (se Fig. 2). Xogle betydelig mindre Muskler 

 passerer fra Hovedets dorsale Integument til For- 

 siden af Kindbakkerne. 



Xogen Underlæbe har det ikke lykkets mig at 

 paavise. Prof. Lilljeborg tror dog at have fundet 

 den i Form af 2 meget smaa tilspidsede og tæt haa- 

 rede Lappe. 



Første Par Kjæver (Fig. 2, 4, 9, m\ Fig. 10) 

 bestaar af en kort og tyk Basaldel og en meget 

 bevægelig indadboiet, skiveformig Endedel, der paa 

 sin frie Kand er besat med en tæt Rad af tynde, 

 leformigt krummede Børster, alle tydeligt 2deddede 

 og fint cilierede. Foruden dem findes der endnu en 

 Rad af betydelig kortere Børster eller Pigge, der er 

 grovt tandede i Kanterne og ender i en særdeles fin 

 og delicat Spids (se Fig. 11). Disse Bor.ster er dog 

 kun indskrænkede til den bagre Halvdel af Randen. 

 Endelig bemærkes fortil, i Vinkelen mellem Basal- 

 delen og Endelaraellen en meget liden, men tydeligt 

 begrændset, seenndær Lamelle af smal tungedannet 

 Form og kantet med nogle ganske korte Børster. 



Andet Par Kjæver (Fig. 2, 4.9, ;;/-, Fig. 12, 13) 

 er betvdelig mindre end Iste Par og, som det synes, 

 kun lidet bevægelige. De bestaar ligeledes af en 

 kort Basaldel og en indadrettet Endelamelle af 

 elliptisk Form, med det indre afrundede Hjørne lie- 

 tvdelig mere fremspringende end det ^•dre. Lamellen 

 er kantet med omkring 24 tæt cilierede Børster, som 

 dog er utydeligt leddede og kun mod det indre 

 Hjørne naar nogen betj'delig Længde. 



Af Fodder har jeg hos fnldt udviklede Lidivider 

 talt 22 — 23 Par. Prof. Lilljeborg har hos ualniin- 

 delig store Exemplarer endnu fundet et Par bag 

 disse, saa at deres Tal kan stige til 24 Par ialt; ja 

 Grube paastaar endog hos et Individ at have talt 

 26 Par. De er idethele af en meget uniform Byg- 

 laing og viser alle ( 'haraeteren af ægte Branchial- 

 fødder. Foruden til Re.spiration, har de imidlertid 

 ogsaa en væsentlig Betydning ved Næringsoptagel- 

 sen, idet de i Våndet værende organiske Smaadele, 

 hvoraf Dyret nærer sig, ved Føddernes rhytmiske 

 Bevægelser bliver livirvlet ind mod Munddelene. 

 De 10 eller 1 1 forreste Par er nogenlunde af samme 

 Længde, men fra det Ilte Par begynder de stærkt 

 at aftage i Størrelse, og de allerbagerste Par er 

 overmaade smaa og vanskelig at tælle. De har alle 



liroad, tinely-riuted molar surfare without a trace of 

 dentate projections. Be.sides the powerful adductor 

 miTseles, wliich fill the greater part of the inner 

 cavity of tlie body, a few other muscles are also 

 seen jiassing to the mandibles, wliick» by their aid, 

 can turn upon their axis within certain limits. The 

 strongest of tliese rotatory muscles issue from the 

 dorsal .surface of the cervical segment, and converge 

 towards the posterior side of the mandibles (see 

 fig. 2). Some much smaller muscles pass from the 

 dorsal integument of tlie head to tlie anterior side 

 of tlie mandibles. 



I have not succeeded in proving the presence 

 of any posterior lip. Prof. Lilljeborg, however, be- 

 lieves that he has found it in the shape of two very 

 small, pointed, and dense!}' hairy lobes. 



The first jiair of maxillæ (figs. 2, 4, 9, ?h\ fig. 

 10) consist of a short and thick basal part, and a 

 very movable, incurved, lamellar, terminal part, 

 which is clothed on its free margin with a close 

 row of thin, falciformly curved bristles, all distinctly 

 2-jointed and finel\' ciliated. In addition to these, 

 there is yet another row of much shorter bristles 

 or spines, which are coarsely dentated at the edges, 

 and end in a particularly fine and delicate point 

 (see fig. 11). These bristles, however, are only con- 

 fined to the posterior half of the margin. Lastly, 

 there is visible in front, in the angle between the 

 basal part and the terminal lamella, a very small, 

 but distinctly defined lamella, of a narrow lingular 

 form, and edged with a few very short bristles. 



The 2nd pair of maxillæ (figs. 2, 4, 9, »i'^, figs. 

 12, 13) are consideral>l\' smaller than the first pair, 

 and apparently only sligiitly movable. They also 

 consist of a short basal part, and an inward-direc- 

 ted terminal lamella of elliptical shape, with the 

 inner rounded corner considerably more prominent 

 than the outer one. The lamella is bordered with 

 about 24 thickly ciliated bristles, which are how- 

 ever, indistinctly articulated, and only at the inner 

 corner attain any considerable length. 



In fully develo}ied animals, I have counted from 

 22 to 23 pairs of legs. Prof. Lilljeborg has even 

 found a pair behind these in unusually lai'ge speci- 

 mens, so that their number can rise to 24 pairs in 

 all ; indeed, (rrube asserts that in one specimen he 

 has counted as many as 2G pairs. The}' are, on 

 the whole, of a very uniform structure, and exhibit 

 all the characters of true branchial legs. They are, 

 however, of essential importance, not onl}' in respi- 

 ration, but also in the admission of nourishment, as 

 the organic particles in the water, on which the 

 animal feeds, are whirled in towards the oral parts 

 by the rhythmical movements of the legs. The 10 

 or 11 foremost pairs are of about equal length, biit 

 after the 11th pair they begin to diminish rapidly, 

 the hindmost ]>airs being exceedingly small and 



