77 



Indre Organer. 



Fordøielsessystemet. — Tarmp)i danner (.«c Tal). 

 XIII, Fiy. 1, 2; et simpelt og temnielie; vidt, bagtil 

 noget afsmalnende Rør, der straikker sig igjeniiem 

 Axen af Legemet, og iidmimder. etterat lia ve dan- 

 net en kort Endetiirm, ved Enden af sidste Hale- 

 segment, nnder Basis af Halepladen. Paa Ihider- 

 siden af dens forreste stnmpt afrnndede Del minider 

 .Spiseroret, der er stærkt mnscnlost og stiger lodret 

 i Veiret fra Mnndaahningen. Dets ovre Knde s]>rin- 

 ger frit frem i Tai'mens Lumen, og viser lier en 

 eiendommelig kla]>formig Indretning ise Tab. XII, 

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

 fra at passere tilbage ind i Sj)iseroret. Med den 

 forreste Del af Tarmen forbinder sig et meget coni- 

 pliceret leveragtigt Oi'gan, der iylder en stor Del af 

 Hovedet (se Tab^ XIII, Fig. 1, :>, 1). Det bestaar 

 af 2 symetriske Halvdele, hver delt i talrige nregel- 

 mæssigt forgrenede Blindsa-kke (Fig. o), der er nd- 

 klædt indvendig med et Lag af glandulose Cellf^r. 

 Alle dis.se Blinds.ekke samler sig tilsidst ]iaa hver 

 >Side til en fæl les kort Stamme, der mnndei- i den 

 forreste Del af Tarmen. Det hele Apparat svarer 

 utvivlsomt til de 2 forholdsvis simple blindsa^-k- 

 formige Udvidningei' af Tarmen hos Branehipodi- 

 derne. 



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

 get langstrakt Form, og strækker sig igjennem hele 

 Midtkroppen, fra Mandibularsegment og ind i Ilte 

 fodbærende Segment. Sfim sædvanligt, ligger det 

 umiddelbart ind nnder Kroppens dorsale Integniment, 

 og afsmalnes gradvis forfra bagtil, hvor det .synes 

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

 ning, hvorigjennem Blodet drives ud i Hovedet og 

 derfra i Ivygskjoldet og den ovrige Krop. For hvert 

 Kropssegment har det et Par venose Syialter, for- 

 .synede med 2 khqiformige, bevægelige La'i)er, der 

 afvexlende lukker og aabner sig, og hvoriniellem 

 Blodet ojitages i Hjertet fra de forskjellige Dele af 

 Ijegemet. I Ii_\-gskj(d(let tinder en meget livlig l^>lod- 

 eireulation Sted, og iihidet gjenneiiistrnmmer her et 

 meget eoni]diceret Sy.stem af Hiilrum, beliggende 

 mellem d(> 2 Lamellei-, hvoraf ivygskjoldet er sam- 

 mensat. Nogen virkelige i>lodk:ir existerer imidler- 

 tid ligesiialidt her scjiu hos andre l'liylln])iid(>r. 



Nervesystemet. — Som hos andre Krebsdyr, be- 

 .staar Nerves\stemets Centraldele af det ovre Svælg- 

 ganglion, eller Hjernegangliet, og en Bugganglie- 

 kjæde. Hjernegangliet er meget vanskeligt. at un- 

 dersoge, da det ligger tæt omhyllet af andre Dele. 

 Saavidt jeg har kunnet se veil omhyggelig Dissec- 

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

 og af betydelig simjilere Bygning end hos i^ranehi- 

 podiderne, nden de hos disse forekommende dorsale 



Internal Organs 



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

 tigs. 1, 2) is in the form of a simple, ratlier wide 

 tnlie, slightly tajiering jiosteriorly, 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 

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

 rounded part, o]>ens the (esophagus, which is excee- 

 dingly muscular, and rises jierpendicularly from the 

 oral ajierture. Its npjier end projects freely into 

 the lumen of the intestine, exhibiting there a pecu- 

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

 11, (p), whereby tlie contents of the intestine are 

 prevented from passing liadc into the (esophagus. 

 A\'ith the foremost jiart of the intestine is connected 

 a very conqdiciited hejiaticous organ, wlii( li occupies 

 a great part of the head (see PI. Xlll. rigs. 1. 2. 1). 

 It consists of 2 symmetrical halves, each divided 

 into numerous ii'regularly ramified cæca (rig. 3), 

 wliidi are lined iiitei'iorly with a stratum of glan- 

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

 side, into a slmrt cdnimon stem that opens into the 

 anterior jiart of the intestine. Tlie wh(de a])]iaratus 

 undoubtedly answers to the two comparatively 

 simple cæcum-like expansions of the intestine in 

 the Branilii|i(idi(he. 



Vascular system. — The heart ,rig. 1, 2, e) is 

 of a very idongated shape, and extends tliroughout 

 the mesosome, from the mandibular segment into 

 the 11th ])edigerous segment. It lies, as usual, imme- 

 diately bidow the dorsal integument of tiie body, 

 and tapers gradually from the front to the back, 

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

 contrary, it has a wide o])eiiing, througli which the 

 blood is dri%en out into the head, and tiience into 

 the carapace and tlie rest of the body. In each 

 segment of the iiiesosonie there are two venous 

 ostia, ea( h furnished with 2 valve-like movable lijts, 

 which alternately open and shut, and through which 

 the blood is received into the heart from the dilt'e- 

 rent ])arts nf the liod\'. .\ vei-y active circulation 

 takes place in tlu» carapace, the blood flowing 

 through a ver\' complicated system of cavities lying 

 lietween the 2 lamclhe of whidi the carapace is 

 com])oscd. Actual blood-vessels, however, ni> more 

 exist lierc than in other Ph\llo]ioda. 



Nervous system. — As in other crustaceans, the 

 central ])ortion ot' the nervous .system I'onsists of an 

 uj)per (esophageal ganglion, (n' cerebral ganglion, and 

 a ventral ganglion diain. The cerebral ganglion is 

 very dillicult to examine, as it is closely enveloped 

 by other jiarts. As far as 1 have been aVile to see 

 bv careful dissection, it is eonijiaratividy small i,Pl. 

 XIII, fig. ;"), gK and of a much simpler structure 

 than in the Branchijiodidæ, without the dorsal lobes 



