119 



hertil saaledes: ,,Wegen «ln- fast steinhartigen Earte der 

 Mauerblattes lassen die Polypen keine (Jntersuchung mittelst 

 der Schnittmethode zu, und wandte ich deshalb auch hier 

 die Schliffmethode von v. Koch an". Der var dog blandt 

 mine Exemplarer enkelte, der vare mindre stærkt inkruste- 

 rede. saa at jeg kumle erholde adskillige ret gode Tversnit, 

 og i det Hele tåget viser Hudens Inkrustation sig hos 

 Mardcell Erdmanni langtfra san stenagtig haard, som Til- 

 fældet maa have været hos Dr. Erdmanns navnløse Slægt. 

 Saa vanskeligt det er at faa brugbare Tversnit, saa lei er 

 det at aabne Polypen etter Længden. 



Animer man to sammenhængende Dyr efter Læng- 

 den, saaledes som Fig. 4. Tab. XXII adviser, sees begge 

 Polyper ikke at staa i direkte Forbindelse med hinanden, 

 men at hver for sig har sin bestemte Afgrændsning, der 

 danner Polypens egentlige Bund, Tab. XXII. Fig. 3 a, 

 4 a, og som bestaar af en skiveformel Fortykkelse af Huden, 

 hvori Sandkorn ere inkrusterede ; det er Coenenchymet for 

 disse to Polyper. og hvori tindes Kanaler, som korrespon- 

 dere med begge Polypers Kamre, saa at Fluidumet i den 

 ene Polyp med stor Lethed kan gaa over i den anden 

 Polyps Gastralhulhed. 



Fra Polypens Bund udgaar 18 Macroseptaer, der ved 

 deies Udspring ere temmelig smale. Tab. XXII. Fig. 3 b, 

 men tiltage snart i Bredden, eftersom de naa længere frem 

 (op) paa Kroppen. Tab. XXII, Fig. 3 c. 4 c, og blive 

 bredest henimod Mundskiven, strax førend de fæste sig 

 paa Svælgrøret, Tab. XXII, Fig. 4 d. Disse 18 Macro- 

 septa ere fuldstændige Septa, der dele Gastrovascularhul- 

 heden i 18 Længdekamre, som foroven ere lukkede, imedens 

 de forneden gaa over i de føromtalte Kanaler i Coenen- 

 chymet, Tab. XXII, Fig. 3 d. 



Imellem hver 2 af Macroseptaerne er der 1 Microsep- 

 tum. saa at der af disse ligeledes er 18. Tab. XXII, Fig. 7. 

 De tåge deres Udspring nogle Millimeter ovenfor Polypens 

 Bund, ere meget smale, listeformige og tiltage kun lidet i 

 Tykkelse eller Bredde, indtil de have naaet den underste 

 Flade af Mundskiven. paa hvilken de fæste sig, og gaa følge- 

 lig ikke over paa Svælgrøret, Tab. XXII. Fig. 3 e, 4 e. 



Af Macrosepta er der især to, som udpræge sig ved 

 sin stærkere Bygning, staa længere fra hinanden. Tab. 

 XXII. Fig. 7 a, og fæste sig et paa hver Siderand af 

 Svælggruben, Tab. XXII. Fig. 7 b, der repræsenterer Bug- 

 siden; disse Septa kunne betragtes som Retningssepta. 

 Ligeledes er der to Microsepta, som strække sig henimod 

 Svælgrørets Rygside uden at fæste sig paa det, Tab. XXI, 

 Fig. 17 /i; Tab. XXII, Fig. 7 c; disse Septa kunne ogsaa 

 ansees som Retningssepta.; de ere stillede ganske modsat 

 dem paa Bagsiden, staa. temmelig langt fra hinanden og 

 imellem to Macrosepta. 



Vil man nu betragte disse Septa parvis, hvilket 

 synes mig noget sogt, og hvorover jeg senere kommer 



himself in regard to this, as follows: „Wegen der tast 

 steinhartigen Harte der Mauerblattes lassen die Polypen 

 keine (Jntersuchung mittelst der Schnittmethode zu, und 

 wandte ich deshalb auch hier die Schliffmethode von v. 

 Koch an". There were, however, among my specimens, a 

 fen that were less encrusted than the others, so that I 

 was enabled to obtain several fairly satisfactory sections; 

 and. altogether, the encrustation of the integument of 

 Mardcell Erdmanni do.es not appear to be so siliciously hard 

 as must have been the case with Dr. Erdmann's nameless 

 genus. .lust as difticult as it is to obtain available transverse 

 sections. as éasj is it to dissecl the polyp longitudinally. 



If we open two united animals longitudinally. as shown 

 in hg. 4, Pl. XXII. it is seen that both the polyps do not 

 stand in direct connection with each other, but that each of 

 them has, tor itself, its own definite demarcation, forming the 

 real base of the polyp (Pl. XXII, fig. 3 «, 4 a); the latter 

 — the base — eonsists of a discoidal tumification of the 

 integument, in which grains of sand are encrusted; this 

 tumification is the sarcosoma of those two polyps, and in 

 it an' found ducts that correspond with the chambers of both 

 polyps, so that the Huid of the one polyp can with great facility 

 be passed over into the gastral cavity of the other polyp. 



From the base of the polyp 18 macrosepta issue, 

 which at their origin are rather narrow (Pl. XXII. fig. 

 3 b) but soon increase in breadth as they extend farther 

 forward (upwards) on the body (Pl. XXII. fig. 3 <•■, 4 c), 

 and become broadest towards the oral disc. immediately 

 before they attach themselves to the gullet-tube (Pl. XXII, 

 fig. 4 d). Those 18 macrosepta are perfect septa, which 

 divide the gastro-vascular cavity into 18 longitudinal cham- 

 bers that are closed at the top, whilst at the foot they 

 pass over into the ducts in the sarcosoma previously spoken 

 of (Pl. XXII. fig. 3 d). 



Between each 2 of the macrosepta there is one micro- 

 septum, so that there a ro also 18 of them (Pl. XXII, 

 fig. 7). They have their origin a few milliinetres above 

 that of the polyp: they are verv narrow. fillet-formed, and 

 only increase a little in thickness. or breadth. before they 

 have reached the inferior surface of the oral disc, to which 

 they attach themselves. and consequently do not pass over 

 to the gullet-tube (Pl. XXII. fig. 3 e. 4 e). 



Of the macrosepta there are two that especially dis- 

 tinguish themselves by their stronger structure, stand 

 farther apart from each other (Pl. XXII. rig. 7 o), and 

 which secure themselves, one on each lateral margin of 

 the gullet-groove (Pl. XXII, fig. 7 b) that represents the 

 ventral side; these septa may be considered as directive 

 septa. There are also two microsepta that extend them- 

 selves towards the dorsal side of the gullet-tube without 

 attaching themselves to it (Pl. XXI, fig. 17 b; Pl. XXII, 

 fig. 7 c); these septa may also be considered as directive 

 septa; they are placed quite the contrary of those on the 

 ventral side, and are placed at a considerabjfi distance 

 apart from each other and between two macrosepta. 



If we no w consider these septa in pairs, a thing 

 which appears to me to be somewhat tar-fetched — and 



