93 



Spor af tamlformige Fremspring. Foruden de kraf- 

 tige AddiTctormuskler, der fylder Storsteparten af 

 den indre Hulhed af Corpus, sees ogsaa en Del 

 andre Muskler at passere til Kindbakkerne, ved 

 Hjælp af hvilke disse kan dreies ora sin Axe inden 

 visse Grændser. De stærkeste af disse Rotations- 

 muskier udspringer fra den dorsale Flade af Nakke- 

 segmentet og convergerer mod Kindbakkernes bagre 

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

 passerer fra Hovedets dorsale Integument til For- 

 siden af Kindbakkerne. 



Nogen Ilnderlæbe har det ikke 13'kkets mig at 

 paavise. Prof. Lilljeborg tror dog at have fundet 

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

 rede Lappe. 



Forste 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 Rand er besat med en tæt Rad af tynde, 

 leformigt krummede Borster, alle tydeligt 2-leddede 

 og fint cilierede. Foruden dem findes der endnu en 

 Rad af betydelig kortere Borster eller Pigge, der er 

 grovt tandede i Kanterne og ender i en særdeles fin 

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

 kun indskrænkede til den bagre Halvdel af Rauden. 

 Endelig bemærkes fortil, i Vinkelen mellem Basal- 

 delen og Endelamellen en meget liden, men tydeligt 

 begrændset, secundær Lamelle af smal tungedannet 

 Form og kantet med nogle ganske korte Bor.ster. 



Andet Par Kjæver (Fig. 2, 4,9, rn'', Fig. 12, 13) 

 er betydelig 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 Hjorne be- 

 tydelig mere fremspringende end det ydre. Lamellen 

 er kantet med omkring 24 tæt cilierede Borster, som 

 dog er utydeligt leddede og kun mod det indi-e 

 Hjorne naar nogen betydelig Længde. 



Af Fodder har jeg hos fuldt udviklede Individer 

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

 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- 

 ning og viser alle Characteren af ægte Branchial- 

 fodder. Foruden til Rcsj^iration, har de imidlertid 

 ogsaa en væsentlig Betydning ved Næringsoptagel- 

 sen, idet de i Våndet værende organi.ske Smaadele, 

 livoraf Dyret nærer sig, ved Foddernes rhytmiske 

 Bevægelser bliver hvirvlet ind mod Munddelene. 

 De 10 eller 1 1 forreste Par er nogenlunde af samme 

 Længde, men fra det Ilte Par begynder de stæi'kt 

 at aftage i Storrelse, og de allerbagerste Par er 

 overmaade smaa og vanskelig at tælle. De har alle 



broad, finely-fluted molar surface without a trace of 

 dentate projections. Besides the powerful adductor 

 muscles, which fill the greater part of the inner 

 cavity of the body, a few other muscles are also 

 seen passing to the mandibles, which, by their aid, 

 can turn upon their axis within certain limits. The 

 strongest of these 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 the head to the anterior side 

 of the 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 densely hairy lobes. 



The fii'st pair of maxillæ (figs. 2, 4, 9, »«', 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 finely 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 po.sterior 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, m^, figs. 

 12, 13) are considerably smaller than the first pair, 

 and apparently only slightly movable. They also 

 consist of a short basal part, and an inward-dii'ec- 

 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 developed animals, I have counted from 

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

 found a pair behind these in unusually large speci- 

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

 all; indeed, Grube asserts that in one specimen he 

 has counted as many as 26 pairs. They 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 only 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, but 

 after the 11th pair they begin to diminish rapidly, 

 the hindmost pairs being exceedingly small and 



