19 



Omkring siphoncrne i nogen afstand fra disse 2 tætte mu- 

 skelringe, omtrent i hoide med ringfuren (tia;. 13). 



Præbranchialzonen glat og megyt smal ved flimregru- 

 ben og lier lulen udbugtning; den bliver efterhaanden 

 bredere mod endostylen (fig. 14). 



Tentakler ca. IS, hvoraf lo storre, meget svagt 

 grenede. 



Flimrcgruben liden, enkelt l)ygget med svagt boiet 

 aalming, hvis konkave side vender fortil og tilvenstre 

 (tig. 14). 



Gangliet tret bag Himregruben, iioget tilhoire for 

 denne. 



Dorsalfolden glat og med omboiet, glat rand; den 

 lober langt forbi svælget, som sædvanlig paa dettes venstre 

 side. 



Gjællesækken er meget fin, paa hver side med 7 hoie 

 fine længdebaand, som er fæstede til de høie tværribber, 

 men ellers svæver frit over toppene af infundibnla og med 

 8 længderækker af disse; hvert infnndibularsystem dannes af 

 2 spiralsnoede spirakler. hvis ender er forsynede med for- 

 tykket epithel og derfor især paa farvede præparater sees 

 kolk'formigt fortykkede. Under hveranden tværribl)e tager 

 si)iraklerne sin begyndelse, og man ser derfor her i hjør- 

 nerne mellem 4 infundibnla 4 noget bøiede, opsvulmede 

 spirakelender; de fra disse udgaaende spirakler danner nu 

 de dobbelt spiralsnoede infundibnla paa hver side af tvær- 

 ribben, saaledes som fig 15 viser. Denne anordning er 

 overalt streng lovniæssig. Fra infundibnla s jijorner lober 

 fine radiære baand op til spiralernes toppe, intermediære 

 saadanne er ogsaa almindeligt tilstede. ]\rellcni de af 2 

 spirakler dannede spiraler findes kun fine baand, ikke bre- 

 dere end baandeiH! i spiralerne selv; disse er meget smale og, 

 idet spiraklerne hver gjør 6 — 7 omgange, finder man 12- -15 

 saadanne. Infundibnla er næsten kvadratiske, temmelig høie 

 og tiltager efterhaanden i størrelse fra dorsalfolden mod 

 endostylen (U.T — 1.4 mm. brede); i den nærmest endostylen 

 lobende læugderække har infundibnla delt sig i to mindre 

 (t.).ii mm. brede). Der findes som nævnt paa hver side S 

 længderækker med infnndibula, men kun 7 længdeliaand, 

 idet den nærmest dorsalfolden forlobende række ikke er 

 overdækket med nøset baand. 



Svædget ligger nærmere fiiniregruben enil gjællesækkens 

 hund. ffisophagus kort, niesten lodret stillet; den foldede 

 mave gaar uden indsnæ^vring (jver i tarmen, der danner en 

 hoi slynge (i hoide med svælget) ; tarmslyngens nedadlohende 

 del sænker sig saa dybt ned, at den opadstigende rectum 

 næsten dækker maven <jg æsophagus. 



Anus er fastvokset; dens frie rand er svagt omboiet 

 og fint lappet. 



Kjonsorganet i tarmslyngen, gaar herfra over den 

 nedadlohende del af denne (paa indsiden), hoier sig derpaa 

 opad og lægger sig tæt op til maven. Seet inilenfra ligner 



curve of the intestine. Round the siphons, but at sorae 

 distance from them, there are 2 dense muscular rings at 

 about the level of the peripharyngeal band (fig. 13). 



Præbranchial zone smooth, rather narrow and without 

 protuberances at the ilorsal tubercle, hecoming gradually 

 broader towards the endostyle (fig. 14). 



Tentacles about 18 in nuniber, of which lo are large 

 and very slightly ramified. 



Dorsal tubercle small, simple in structure. and witli 

 a slightly curved opening, the concave side of which is 

 turned forwards and to the left (fig. 14). 



The ganglion is close beliind, and somewhat to the 

 right of the dorsal tubercle. 



The dorsal lamina is smooth, and with smooth, down- 

 ward-bent margin; it runs far beyond the æsophageal aper- 

 ture, as usual on its left side. 



The branchial sac is very delicate, witli 7 higli, deli- 

 cate longitudinal bands on each side attached to the high 

 transverse bars, but in other respects hanging freely over 

 the tops of the infundibnla, of which there are 8 longitu- 

 dinal rows. Each infundibular system is formed by 2 

 spirally-twisted spiracles, whose ends are fnrnished witii 

 thickened ejjithelium, and therefore, especially in coloured 

 specimens, apjiear clavate. The spiracles begin under 

 every alternate transverse bar, and therefore, in the corners 

 between 4 infundibnla, are seen 4 somewhat curved, swollen 

 spii'acle ends. The spiracles issuing from these now form 

 the twice spirally twisted infundibnla on each side of the 

 transverse bars, as shown in fig. 15. This arrangement 

 always follows a fixed rule. From tlu^ corners of the in- 

 fundibnla, fine radiating bands run U[) to the top of the 

 spirals, intermediate ones being also present. Between the 

 spirals formed by 2 spiracles, there are only fine bands, 

 no broader tlian the liands in the spirals themselves; the 

 latter are very narrow, and, as the spiracles make 6 or 7 

 convolutions, from 12 to 15 in number. Tlic infnndibula 

 are rather deep, and almost sqnare, and they gradually 

 increase in size from the dorsal lamina to the endostyle 

 (0.7 — 1.4 mm. broad). In the longitudinal row nearest the 

 endostyle. each infundilndnm is divided into 2 smaller ones 

 (U.ii mm. broad). As before mentioned. there are 8 longi- 

 tudinal rows of infnndibula, but only 7 longitudinal bands, 

 the row nearest to the dorsal lamina not lieing covered 

 with any band. 



The æsophageal aperture is situated nearer to the 

 dorsal tubercle than to the bottom of the branchial sac. 

 The æsophagus is short and almost vertical in position. 

 The folded stoniach passes without any constriction into 

 the intestine, which ioims a high loop (on a level with 

 the æsophageal aperture), the descending portion of the 

 loop sinking so low that the ascending rectum almost covers 

 tile stoniach and the æsophagus. 



The anus is fixed, its free margin slightly curved and 

 finely lobed. 



The genital organ is in the intestinal loop, passing 

 from thence into its descending portion (on the inside) and 

 then curving npwards and lying close to the stoniach. 



3* 





