57 



Sider af Stammen, hvis Ende (som man hos Synapta 

 har kaldet Tommelfinger) rager frem foran eller 

 ud over hine Grene, medens de hos Myriotrochus, efter 

 Steenstrups Beskrivelse og Afbildning (1. c. fig. 9), synes 

 ligesom hos Chirodota at være i Enden skive- eller haand- 

 dannede (tentacula peltato-digitata), idet deres ydre Halv- 

 del er bredere, affladet paa den ydre Side, og Randen be- 

 sat med fingerförmige Grene og uden nogen ud over disse 

 fremragende Ende (Tommelfinger) af Stammen. 



Jeg foreslaar derfor Navnet Oligotrochus (formedelst 

 det ringe Antal af Kalkhjul) for den nye Slægt, som kunde 

 charactericeres saaledes: 



Oligotrochus M. Sars, novum genus e Holothuridarum 

 apneumonum et apodum ordine. 



Corpus crassiusculum seu haud multo elongatum, teres, 

 subcylindricum aut subfusiforme, cute tenui, glaberrima, 

 præter corpuscula perpaucaminutissima calcarea,rotiformia, 

 multiradiata, singula (non acervatim accumulata), sparsa, 

 non petiolata, secl cuti immersa, laminis calcareis destitu- 

 tum. Discus oralis paulo inclinatus. Tentacula 12, in partern 

 eorum basalem qvasi in vaginam retractilia, non autem in 

 corpus abscondenda, brevissima, elongato-conica, utrinqve 

 digitata. Musculi corporis longitudinales 5 gracillimi, duo 

 dorsales (bivium) magis approximati qvam ceteri fere ækvi- 

 distantes (trivium). Intestinum ansam duplicem componens. 

 Os anticum, subventrale; anus posticus circularis, haud 

 lobatus. Vesica Poliana unica; tubercula madreporiformia 

 1 — 3. Tubi genitales ramosi, breves, crassi, fasciculos duos 

 componentes. Annulus calcareus pharyngeus bene evolutus, 

 humilis, e laminis ut videtur 10 constans intime connatis, 

 fere æqve latis, ventralibus altioribus, dorsalibus humilio- 

 ribus, margine anteriore cuspidibus 12 triangularibus ornato. 



O. vitreus M. Sars. 



Corpus antice parum, postica magis angustatum, paulo 

 curvatum, dorso convexiore, prorsus hyalinum, subrigidum, 

 50 Mm. longum, medio 12 — 13 Mm. crassum. Tentacula 

 utrinqve digitis 4, raro 5, parvis, basin versus brevioribus. 

 Corpuscula calcarea rotiformia solummodo prope extremi- 

 tates corporis sita, minutissima (oculo nudo inconspicua), 

 subconcava seu subcupuliformia, multiradiata, dentata; an- 

 nulo rotæ e particulis æqvalibus (17 — 24) composito, una- 

 qvaqve dente magno elongato-conico introrsum verso mu- 

 nita; radiis qvam illis paucioribus (10 — 16), cylindricis, sub- 

 arcuatis, in umbonem medium convergentibus. 



Habitat haud freqvens in sinu Chris ti aniensi ad Drø- 

 bak et Vallø in profunditate limosa 50—200 orgyarum, 

 nec non ad Skraaven, insulam Lofotensem, usqve ad 300 

 orgyas. 



FORKLARING AF FIGURERNE. 



Tab. 7, Fig. 1 forestiller Oligotrochus vitreus seet fra Siden og 

 noget ovenfra; a de contraherede Tentakler; o en af de 

 dorsale Længdemuskler; c en af de ydre ventrale Længde- 

 muskler; d d Tarmcanalen; e Generationsorganerne; f den 

 lille cylindriske Papille, hvorpaa disse udmunde. 



Fig. & Et andet Individ seet fra den venstre Side, fuldt udstrakt 



sides of the stem, the extremity of which (called in the 

 Synapta the thumb) projects before or beyond these bran- 

 ches, while in the Myriotrochus according to Steenstrup's 

 description and delineation (1. c. fig. 9) they seem as in the 

 Chirodata to be disc-like or hand-shaped at the extremity 

 (tentacula peltato-digitata) their outer half being broader 

 and flattened on the outside, and having finger-like bran- 

 ches on the margin, without any projecting extremity of 

 the stem thumb beyond them. 



I suggest therefore the name Oligotrochus (on account 

 of the small number of calcareous wheels) for the new ge- 

 nus which may be characterised as follows. 



Oligotrochus M. Sars. Novum genus e Holothuridarum 

 apneumoneum et apodum ordine. 



Corpus crassiusculum seu haud multo elongatum, teres, 

 subcylindricum aut subfusiforme, cute tenui, glaberrima, 

 præter corpuscula perpauca minutissima calcarea, roti- 

 formia, multiradiata, singula (non acervatim accumulata), 

 sparsa, non petiolata, sed cuti immersa, laminis calcareis 

 destitutum. Discus oralis paulo inclinatus. Tentacula 12, 

 in partem eorum basalem qvasi in vaginam retractilia, non 

 autem in corpus abscondenda, brevissima, elongato-conica, 

 utrinqve digitata. Musculi corporis longitudinales 5 gra- 

 cillimi, duo dorsales (bivium) magis approximati qvam 

 ceteri fere æqvidistantes (trivium). Intestinum ansam du- 

 plicem componens. Os anticum, subventrale; anus posti- 

 cus, circularis, haud lobatus. Vesica Poliana unica; tuber- 

 cula madreporiformia 1 — 3. Tubi genitales ramosi, breves, 

 crassi, fasciculos duos componentes. Annulus calcareus 

 pharyngeus bene evolutus, humilis, e lamimis ut videtur 10 

 constans intime connatis, fere æqve latis, ventralibus altis- 

 ribus, dorsalibus humilioribus, margine anteriore cuspidi- 

 bus 12 triangularibus ornato. 



O. vitreus M. Sars. 



Corpus antice parum, postice magis angustatum, paulo 

 curvatum, dorso convexiore, prorsus hyalinum, subrigidum, 

 50 Mm. longum, medio 12—13 Mm. crassum. Tentacula 

 utrinque digitis 4, raro 5, parvis, basin versus brevioribus^ 

 Corpuscula calcarea rotiformia solummodo prope ex- 

 tremitales corporis sita, minutissima (oculo nudo inconspi- 

 cua), subconcava seu subcupuliformia, multiradiata, den- 

 tata; annulo rotæ e particulis æqvalibis (17—24) compo- 

 sito, unaqvaqve dente magno elongato-conico introrsum 

 verso munita; radiis qvam illis paucioribus (10—16), cylin- 

 dricis, subarcuatis, in umbonem medium convergentibus. 



Habitat haud freqvens i sinu Christianiensi ad Drøbak 

 et Vallø in profunditate limosa 50 — 200 orgyarum, nec non 

 ad Skraaven, insulam Lofotensem, usqve ad 300 orgyas. 



EXPLANATION OF THE FIGURES. 



Tal). 7, fig. 1, represents Oligotrochus vitreus slightly magnified, 

 viewed from one side and a little from above, a the 

 contracted tentacles; o one of the dorsal longitudinal 

 muscles; c one of the exterior ventral longitudinal muscles; 

 dd the intestinal canal; e the organs of generation; f the 

 small cylindrical papilla in which is their outlet. 



Fig. 2* Another specimen viewed from the ventral side, fully 



8 



