154 



at de Forskjelligheder, som skulle begrunde en ny Slægt, 

 maa ikke være enkelte ydre eller indre Afvigelser fra 

 Grundtypen; men maa være af en Organismen mere gjen- 

 n em trængen de Natur. 



Hvad nu de nye Arter under Slægten Phascolion be- 

 træffer, saa have vi Grund til at antage, at de kun ere Varie- 

 teter af Ph. Strombi. Vi have opstillet en Varietet under 

 Navnet Pli. Strombi var. verrucosum, som upaatvivlelig falder 

 sammen med Ph. tuberculosum, Théel, — og Grunden, hvor- 

 for vi ikke af den dannede en ny Art, var simpelthen 

 den, at vi traf flere Overgangsexemplarer, der mere og 

 mere nærmede sig Hovedformen. 



Phascolion spitsbergense, Th., har saameget tilfælles 

 med Exemplarer, vi have fra Vadsø, og som aabenbart 

 ikke ere nye Arter, men vel Varieteter af Strombi, at vi 

 ogsaa med Hensyn til den nære Tvivl om dens Bestaaen 

 som selvstændig Art. Vi kunne imidlertid ikke gaa videre 

 end at fremsætte vore Tvivl og begrunde disse saa godt 

 som muligt; thi vi have ikke været i Besiddelse af Hr. 

 Théels Originalexemplarer. 



Nu skulle vi omtale cle nye Arter af Slægten Phas- 

 colosoma, som Hr. Théel har opstillet. 



Phascolosoma luteum, Th., er sikkerlig, som Dr. Théel 

 selv antager, Kefersteins margaritaceum, der jo er ganske 

 forskjellig fra Sars's margaritaceum; forsaavidt er det i 

 sin Orden, at Théel har givet Arten et nyt Navn. Men 

 da Ph. luteum, Th., og margaritaceum, Keferst., falde 

 sammen med Forbes's Ph. (Syrinx) Harveii, saa formene 

 vi, at Ph. luteum maa ned i Synonymiens Rækker. 



Phascolosoma dubium, Th., har Dr. Théel fundet at 

 Tære usikker — hvilket ogsaa Navnet tyder hen paa — 

 idet han siger, at den nærmer sig Kefersteins elongatum 

 og Blainville's vulgare. Fra disse skal den dog adskille 

 sig ved et lidet større Antal Tentakler, samt ved Mange- 

 len af to Pigmentpunkter (Øienpunkter). Tentaklernes 

 Antal varierer jo særdeles meget, og Pigmentet forsvinder 

 i Regelen temmelig hurtigt ved Opbevaring i Spiritus; 

 ligesom det er meget sandsynligt, at der hos denne Art 

 forekommer Exemplarer, hvor disse Pigmentpunkter mangle, 

 — saaledes er idetmindste Tilfældet med Ph. margarita- 

 ceum, Sars. Vi antage derfor, at Ph. dubium falder sam- 

 men med Ph. elongatum, Keferst. og Ph. vulgare, Blainv. 



Phascolosoma albidum, Th., er vel neppe andet end unge 

 Exemplarer af Ph. margaritaceum, Sars; thi jo yngre In- 

 dividerne af denne Art ere, desto færre ere Tentaklerne, 

 og desto mere gjennemsigtig er Huden. Théel siger og- 

 saa selv, at dersom ikke Danielssen havde angivet indtil 

 .50 Tentakler for Ph. margaritaceum, vilde han ikke have 

 betænkt sig paa at slaa albidum sammen med denne. Og 

 livad nu Phascolosoma fulgens, Th., betræffer, saa adskiller 

 den sig saa lidet fra albidum, at vi have vanskeligt for at 

 se en særskilt Art i den. Vi ere tilbøielige til at tro, at 



is undeniable that this species exhibits greater variations 

 than Ph. Strombi; but for us the requisites for the for- 

 mation of a new genus appear to be greater; as we are 

 of opinion that the differences, which should sanction a 

 new genus, must not be a few external or internal devia- 

 tions from the main type, but must be of a nature to 

 enter more deeply into the organism. 



Now as regards the new species of the genus Phas- 

 colion, we have reason to assume that they are only 

 varieties of Ph. Strombi. We have established a variety under 

 the name Ph. Strombi var. verrucosum, which undoubtedly 

 coincides with Ph. tuberculosum Théel; and the reason 

 why we did not form a new species of it, was simply 

 that we met with several transition-specimens appro- 

 aching more or less nearly to the main form. 



Phascolion spitsbergense Th. has so much in common 

 with specimens that we have from Vadsø, and which are 

 manifestly not new species, but only varieties of Strombi, 

 that we also entertain doubts as to its being maintained 

 as an independent species. We can however not go 

 further than expressing our doubt and justifying it as 

 well as possible; for we have not been in possession of 

 Mr. Théels original specimens. 



Now we shall notice the new species of the genus 

 Phascolosoma, which Mr. Théel has established. 



Phascolosoma luteum Th. is certainly, as Dr. Théel 

 himself supposes, Kefersteins margaritaceum, which is 

 entirely different from Sars' margaritaceum — so far it 

 is quite in order that Théel has given a new name to 

 the species. But as Ph. luteum Th. and margaritaceum 

 Keferst. coincide with Forbes' Ph. (Syrinx) Harveii, we 

 are of opinion that Ph. luteum must fall into the ranks 

 of the synonyms. 



Phascolosoma dubium Th. has been found by Dr. 

 Théel to be uncertain — as also implied by the name — 

 Mr. Théel says it resembles Kefersteins elongatum and 

 Blainville's vulgare, differing from these however by a 

 slightly greater number of tentacles, and by the absence 

 of two pigmentary spots (ocellæ). Now the number of 

 tentacles varies very much; and the pigment usually dis- 

 appears rather rapidly, when specimens are kept in 

 spirit; as likewise there is great probability that specimens 

 of this species may be found in which the pigmentary 

 spots are wanting, — such is at least the case with Ph. 

 margaritaceum Sars. We presume therefore that Ph. 

 dubium coincides with Ph. elongatum Keferst. and Ph. vulgare 

 Blainville. 



Phascolosoma albidum Th. is probably nothing else than 

 young specimens of Ph. margaritaceum Sars; for the 

 younger the individuals of this species are, the fewer are 

 the tentacles and the more transparent is the skin. Théel 

 says also himself that if Danielssen had not indicated up 

 to 50 tentacles for Ph. margaritaceum, he would not 

 have hesitated to place albidum together with it. And as 

 regards Phascolosoma fulgens Th., it differs so slightly from 

 albidum, that it is difficult to see in it a distinct species. 

 W T e are inclined to think that both these species are 



