00 



udgaa radiært fine Folder henimod Tentaklerne, Tab. XII, 

 Fig. 6. Disse sidde i Mundskivens Peripheri i 2 afvexlende 

 Rækker, 24 i hver Række; de ere omtrent saa lange som 

 Mundskivens Bredde. Tab. III. Fig. 7; Tab. XII. Fig. ti. 

 Saavel Tentaklerne som hele den overste, nogne Del kunne 

 trækkes ind i den inkrusterede Skede, og naar Indtræk- 

 ningen er fuldstændig, fremkommer enten en opretstaaende 

 Søile, eller en Halvkugle. hvori den overste Del af Dyret 

 er ganske skjult. 



Farven. Den inkrusterede Del at' Kroppen ei' graa- 

 brun at' den indleirede Biloculinler; den Qøgne Del er bleg 

 rosenrød med stærk Perlemorglands. Mundskiven er blegere 

 med lidt mørkere Striber. Tentaklerne rosenrøde vedGrunden, 

 men deres overste Halvdel er morkere og lidt brunlig. Tab. 

 III, Fig. 7. 



Et Tversnit at' den inkrusterede Kropsde] viser, at 

 der er to Lag udenfor den egentlige Cutis. Det ene Lag, 

 det ydre. bestaar af en meget seig Slimmembran, hvori 

 er indleiret en Mængde fremmede, haarde Legemer, som 

 egentlig danner Krusten, Tab. XII, Fig. 7 a, og indenfor 

 denne en skarp afgrændset, fibrilløs Membran. Cuticula, 

 Tab. XII, Fig. 7 b. der er fast adhæreret til Ectodermet. 

 Dette dannes af temmelig lange Cylindereeller uden Cilier, 

 Tab. XII, Fig. 7 c, imellem hvilke sees mange spredte, 

 encellede Slimkjertler. Indenfor Ectodermet er et bredt, 

 tibrillært Bindevævslag, Tab. XII, Fig. 7 tf. i hvis Midte 

 sees temmelig fine, undulerende, cirkulære Muskelfibriller, 

 Tab. XII, Fig. 7 e, der paa enkelte Steder synes at menne 

 sig Ectodennet, imedens de paa andre nærme sig Entoder- 

 met; tydeligst sees de cirkulære Muskler paa Længdesnit. 



Et Tversnit af den nogne Kropsdel viser, at her 

 ingen Cuticula tindes, men Ectodermet bestaar af lrengere, 

 eilierende Cylindereeller, imellem hvilke baade encellede 

 Slimkjertler og Xematocyster tindes; disse sidste dog ikke 

 i Dogen stor Mængde. Det fibrillære Binde væv er meget 

 bredt, og i dets Midte sees cirkulære Muskeltibre, stærkere 

 udviklede end de, som findes i den inkrusterede Dels Binde- 

 væv. Paa Mundskiven samle de cirkulære Muskler sig 

 omkring Munden, hvor de synes at danne en Sphincter. 

 De longitudinelle Muskler paa Tentaklerne ere fuldstændig 

 ectodermale. 



Der er 6 Par principale, fuldstændige Septa, som 

 staa temmelig langt fra hverandre. Tab. XII, Fig. 12, og 

 af hvilke der er 2 Par Ketningssepta, Tab. XII, Fig. 7 R, 

 12 R, som adskille sig fra de øvrige 4 Par væsentlig der- 

 ved, at de transverselle Muskler ere placerede paa den 

 indre Flade af hvert Septum, Tab. XII, Fig. 1 f, og vende 

 saaledes i hvert intraseptalt Rum imod hverandre. Disse 

 principale Septa tåge deres Begyndelse fra Centrum af 

 Fodskivens indre Flade, hvor de ere vel adskilte og tem- 

 melig smale, men tiltage i Bredde, alt ettersom de komme 

 hengere op paa Kroppen, imedens de longitudinelle Muskler 

 sidde paa den ydre Flade, Tab. XII, Fig. 7 g. Paa de 



margin fine folds issue radially towards the tentacles (Pl. 

 XII, fig. 6). These are seated in the periphery of the 

 oral disc in 2 alternating sei-ies. 24 in each series; they 

 are about as long as the breadth of the oral disc (Pl. III, 

 tig. 7; Pl. XII, fig. 6). Both the tentacles as well as 

 the entire uppermost bare portion, are capable of being 

 withdrawn into the encrusted slieath. and wlien the retrac- 

 tion is c<Smplete, there is produced either a vertical pillar 

 or a hemisphere. in which the uppermost portion of the 

 animal is quite hidden. 



The colour. The encrusted part of the body is grey- 

 brown, from the embedded biloculina clay; the bare por- 

 tion is pale rose-red, with a strong mother-of-pearl bistre. 

 The oral disc is paler, with somewhat darker stripes. The 

 tentacles rose-red at the base, Imt the uppermost half is 

 darker and slightly brownish (Pl. III, fig. 7). 



A transversal section of the encrusted portion of the 

 body shows, that there are 2 layers outside the true cutis. 

 The one layer. the outer one, consists of a very viscid, 

 mucous membrane, in which there are embedded a multitude 

 of foreign hard bodies, that really forms the crust (Pl. 

 XII. fig. 7 a), and inside of it there is a sharply defined 

 fibrillar membrane, cuticulum, (Pl. XII, fig. 7 b) which is 

 firmly adherent to the ectoderm. This latter is formed 

 of rather long cylinder-cells devoid of cilia (Pl. XII, 

 fig. 7 c), between which a multitude of scattered unicel- 

 lular mucous glands are observed. Inside of the ectoderm 

 there is a broad layer of fibrillar connective-tissue (Pl. XLI, 

 fig. 7 d), in whose midd le rather fine, undulating, circular 

 muscle-fibres are seen (Pl. XII, fig. 7 ei which, in some places. 

 appear to approach to the ectoderm. while in other places 

 they approach to the entoderm. The circular muscles are 

 most distinctly seen in longitudinal sections. 



A transversal section of the bare part of the body 

 shows, that no cuticulum is found in it, but the ectoderm 

 consists of longish eiliating cylinder-cells, between which 

 both unicellular mucous glands and nematocysts are found. 

 These last are, however, not present in great abundance. 

 The fibrillar connective-tissue is very broad, and in its 

 middle, circular muscles, more powerfully developed than 

 those in the connective-tissue of the encrusted part, are 

 observed. Upon the oral disc the circular muscles collect 

 themselves round the mouth, where they appear to form a 

 sphincter. The longitudinal muscles on the tentacles are 

 completely ectodermal. 



There are 6 pairs of principal, perfect septa, placed 

 rather far apart from each other (Pl. XII, fig. 12), and 

 of these, 2 pairs are directive septa (Pl. XII, fig. 7 R, 

 12 R) which are distinguished from the other 4 pairs, 

 principally by the transversal muscles being placed on the 

 inner surface of each septum, (Pl. XII, fig. 7 /) and facing 

 thus towards each other in each intraseptal space. These 

 principal septa originate in the centre of the pedal disc's 

 inner surfare, where they are well separated and rather 

 narrow, but they increase in breadth, gradually, as they 

 extend farther up the body; while the longitudinal muscles 

 are seated on the outer surface (Pl. XII, fig. 7 g). On 



