77 



Indre Organer. 



Fordøielsessystemet. — Tarmen danner (se Tab. 

 XIII, Fig. 1, 2) et simpelt og temmelig vidt, bagtil 

 noget af smalnende Eor, der strækker sig igjennem 

 Axen af Legemet, og udmunder, efterat have dan- 

 net en kort Endetarm, ved Enden af sidste Hale- 

 segment, nnder Basis af Halepladen. Paa Under- 

 siden af dens forreste stnmpt afrundede Del nuxnder 

 Spiserøret, der er stærkt mnscnlost og stiger lodret 

 i Veiret fra Mundaabningen. Dets øvreEnde sprin- 

 ger frit frem i Tarmens Lumen, og viser ber en 

 eiendommelig klapformig Indretning (se Tab. XII, 

 Fig. 10, 11, æ), hvorved Tarmens Contenta hindres 

 fra at passere tilbage ind i Spiserøret. Med den 

 forreste Del af Tarmen forbinder sig et meget com- 

 pliceret leveragtigt Organ, der fylder en stor Del af 

 Hovedet (se Tab. XIII, Fig. 1,2, 1). Det bestaar 

 af 2 .symetri.ske Halvdele, hver delt i talrige nre.gel- 

 mæssigt forgrenede Blindsække (Fig. 3), der er ud- 

 klædt indvendig med et Lag af glandnlose Celler. 

 Alle disse Blindsække samler sig tilsidst paa hver 

 Side til en fælles kort Stamme, der munder i den 

 forreste Del af Tarmen. Det hele Apparat svarer 

 utvivlsomt til de 2 forholdsvis simple blindsæk- 

 formige Udvidninger af Tarmen hos Branchipodi- 

 derne. 



Karsystemet. — Hjertet (Fig. 1, 2, c) er af me- 

 get langstrakt Form, og strækker sig igjennem hele 

 Midtkroppen, fra Mandibularsegment og ind i Ilte 

 fodbærende Segment. Som sædvanligt, ligger det 

 umiddelbart ind under Kroppens dorsale Integument, 

 og afsmalnes gradvis forfra bagtil, hvor det synes 

 at ende blindt. Fortil har det derimod en vid Aab- 

 ning, hvorigjennem Blodet drives wå i Hovedet og 

 derfra i Rygskjoldet og den øvrige Krop. For hvert 

 Kropssegment har det et Par venøse Spalter, for- 

 synede med 2 klapformige, bevægelige Læber, der 

 afvexlende lukker og aabner sig, og hvorimellem 

 Blodet optages i Hjertet fra de forskjellige Dele af 

 Legemet. I Rygskjoldet finder en meget livlig Blod- 

 circulation Sted, og Blodet gjennem.strømmer her et 

 meget compliceret System af Hulriim, beliggende 

 mellem de 2 Lameller, hvoraf Rygskjoldet er sam- 

 mensat. Nogen virkelige Blodkar existerer imidler- 

 tid ligesaalidt her som hos andre Phyllopoder. 



Nervesystemet. — Som hos andre Krebsdyr, be- 

 staar Nervesystemets Centraldele af det øvre Svælg- 

 ganglion, eller Hjernegangliet, og en Bngganglie- 

 kjæde. Hjernegangliet er meget vanskeligt at un- 

 dersøge, da det ligger tæt omhyllet af andre Dele. 

 Saavidt jeg har kunnet se ved omhyggelig Dissec- 

 tion, er det (Tab. XIII, Fig. 5, g) forholdsvis lidet 

 og af betydelig simplere Bygning end hos Branchi- 

 podiderne, uden de hos disse forekommende dorsale 



Internal Organs. 



Digestive system. — The intestine (see Pl. XIII, 

 figs. 1, 2) is in the form of a simple, rather wide 

 tube, .slightly ta])ering posteriorly, and extending 

 through the axis of the body; after having formed 

 a short rectum, it opens at the end of the last 

 caudal segment beneath the base of the caudal 

 lamella. On the under side of its anterior, bluntly- 

 rounded part, opens the æsophagus, which is excee- 

 dingly muscular, and rises perpendici;larly from the 

 oral aperture. Its upper end projects freely into 

 .the lumen of the intestine, exhibiting there a pecu- 

 liar valve-like arrangement (see PL XII, figs. 10, 

 11, æ), whereby the contents of the intestine are 

 prevented from passing back into the æsophagus. 

 With the foremost part of the intestine is (connected 

 a very complicated hepaticous organ, which occupies 

 a great part of the head (see PI. XIII, figs. 1, 2, 1). 

 It consists of 2 symmetrical halves, each divided 

 into numerous irregularly ramified cæca (fig. 3), 

 which are lined interiorly with a stratum of glan- 

 dular cells. All these cæca unite at last, on each 

 side, into a short common stem tliat opens into the 

 anterior part of the intestine. The whole apparatus 

 undoubtedly answers to the two comparatively 

 simple cæciim-like expansions of the intestine in 

 the Branchipodidæ. 



Vascular system. — The heart (fig. 1, 2, c) is 

 of a very elongated shape, and extends throughout 

 the mesosome, from the mandibular segment into 

 the 11th pedigeroiis segment. It lies, as usual, imme- 

 diately below the dorsal integument of the body, 

 and tapers gradually ft-om the front to the back, 

 where it seems to have no outlet. In front, on the 

 contrary, it has a wide opening, through which the 

 blood is driven out into the head, and thence into 

 the carapace and the rest of the body. In each 

 segment of the mesosome there are two venoiis 

 ostia, each furnished with 2 valve-like movable lips, 

 which alternately open and shut, and through which 

 the blood i.s received into the heart from the diffe- 

 rent parts of the body. A very active circulation 

 takes place in the carapace, the blood flowing 

 through a very complicated system of cavities lying 

 between the 2 lamellæ of which the carapace is 

 composed. Actual blood-vessels, however, no more 

 exist here than in other Phyllopoda. 



Nervous system. — As in other crustaceans, the 

 central portion of the nervous system consists of an 

 upper oesophageal ganglion, or cerebral ganglion, and 

 a ventral ganglion chain. The cerebral ganglion is 

 very difficult to examine, as it is closely enveloped 

 by other parts. As far as I have been able to see 

 by careful dissection, it is comparatively small (PI. 

 XIII, fig. 5, g), and of a much simpler structure 

 than in the Branchipodidæ, without the dorsal lobes 



