134 



5 oVl» Gautre i Totallængden : den forste Straale i Iste 



Dorsal udgjorde '/a af Hovedlæugdeu. Afstaiiden mellem 

 Snudespidsen og 2den Dorsal indeholdtes omtreut 3.') Gange • 

 i Totallæugdeu. Skjælbeklædningeu var endiiu ikke fuld- 

 stæudig. idet deu' paa Legemets forreste Del øjeusyulig 

 endnu blot var i Frembrud. At M. argeniata blot er 

 en Ungform, er især paa Grund af det sidstnævnte Factum 

 øjensynligt. og det ligger vistnok nærmest at antage den 

 for Ungen af 0. reinhardi. Dette Spørgsmaal kan ikke 

 afgjøres, førend sikre Ungdomsstadier af de 2 uærstaaende 

 Arter, 0. reinhardi og 0. ensis. blive kjendte. 



Viser det sig altsaa i Fremtiden, at Reinhardt's Mo- 

 tella argeniata udgjør Ungformen af O. reinhardi, vil Ar- 

 tens rette Xavu følgelig blive Onos argentatus, (Eeinh.) 

 1838. 



Den nævnte anden Art, Onos ensis, er den, som 0. rein- 

 hurdi i sin udvoxede Stand utvivlsomt staar nærmest. 0. 

 ensis er ligeledes en grønlandsk Form. og opstilledes af 

 Reinhardt (samtidigt med Motella <irgerdata) i Overs. 1835 

 — 36 af det oftere nævnte Selskabs Forhandlinger. 6 Del, 

 p. CX, og senere i 7de Del. p. 116 og 128 (Kbhvn. 1837). 

 efter 2 Individer, der i noget beskadiget Stand i 1 834 vare 

 udtagne af Aentrikelen af en Cgstopliora cristata ved Omenak 

 (70" N. B.). 



Deu af Eeiuhardt paa de ovenanførte Steder gi\Tie 

 korte Characteristik er dog saa ufuldkommen, at Dr. Giin- 

 ther ikke deraf har kuuuet opstille nogen Diagnose, og 

 Arten findes derfor i 1862 i haus Gat. Fish. Brit. Mus. 

 ikke oi3tagen som selvstændig Art (vol. 4, p. 366). De 2 

 originale Exemplarer. der endnu opbevares i det zoologiske 

 Musæimi i Kjøbenluivn. ere fi'emdeles. saavidt vides, de 

 eneste, som existere. og de have hidtil ikke været Gjenstand 

 for nøjagtigere Undersøgelse og Beskrivelse. Ingen af Ar- 

 terne har hidtil været afbildet. 



Ved den flygtige Gjennemgaaelse af denne og de øv- 

 rige nærstaaeude Former, som jeg ved Dr. Liitkens Vel- 

 villie havde Lejlighed til at foretage i October 1878. viste 

 det sig strax, at 0. ensis og 0. reinhardi ere fuldkommen 

 distincte. om end beslægtede Ai-ter. De mest iøjuefaldende 

 Characterer hos 0. ensis ligge i den stærkt forlængede 

 Iste Straale i Iste Dorsal, det mindre Hoved, og den sva- 

 gere Tandvæbuing. Totallængden hos de 2 ludivider var 

 omtreut 31U""" og 392"""'. ^ 



length of the head bears the proportion of 5 — 5'/o. First 

 ray in first dorsal oue-third of the length of the head. 

 Distance from point of suout to second dorsal is to total 

 length as 1 to 3.5. The scales not yet fully developed; 

 on the anterior part of the body indeed almost incipi- 

 ent. Hence. M. argentata must represent one of the 

 earlier stages of gi"owth. in which case it comes nearest 

 to 0. reinhardi. This question cannot, however, be de- 

 cided until the stages through which the two closely 

 related species, 0. reinhardi and 0. ensis, pass before 

 reaching maturity, have become known. 



Should future researches show that Eeinhardt's M. 

 argentata is merely 0. reinhardi in an early stage of dev- 

 elopment, the name of the species will be Onos argentatus, 

 (Reiuh.) 1838. 



Onos ensis is unquestionably the species presenting 

 the closest resemblance to 0. reinhardi in its adult stage 

 of development. 0. ensis is likewise a Greenland form: it 

 was described by Reinhardt (along with Motella argen- 

 tata) in Overs. 1835—36. Kgl. D. Vid. Selsk. Afh. D. 

 6. p. ex. and subsequently in Part 7. jjp. 116 and 128 

 (1837). liis specimens being two individuals, in a some- 

 what mutilated couditiou. which had been taken in 1834 

 from the stomach of a Cystophm-a cristata, near Omenak. 

 in lat. 70» X. 



The brief characterisation furnished by Reinhardt is 

 very imi)erfect however, so much so indeed that Dr. Giinther 

 could not elaborate fi'om it a diagnosis; and the species 

 figures as undetermined in his -'Cat. Fish. Brit. Mus." (vol. 

 4. p, 366). published 1862. The two original individuals 

 still preserved in the Zoological Museum in Copenhagen, 

 are the only specimens known to exist, and up to the pres- 

 ent time they have not been accurately examined and de- 

 scribed. Xeither of the species has hitherto been figured. 



The cursory examination of this and the other nearly 

 related forms which, thanks to the kindness of Dr. Liitken, 

 an opportunity was afforded me of making in October 1878, 

 conclusively proved the specific distinction existing between 

 the congeners 0. ensis and 0. reinhardi. The most conspicu- 

 ous characters in 0. ensis are the produced first ray in 

 the first dorsal fin. the small size of the head, and the feeble 

 dentition. Total length in the two specimens, respectively 

 310'""' and 392™"'.' 



' Onos ensis, i Reinh. i 1 ><X> — ?>tX 



Overs. is:i5— 3(i. Kgl. D. Vid. Selsk. Xatiu-v. Math. Afh. (i Del. 

 p. CX, Kbhvn. 1837 (183.-)— 3fi). 



.y Skjagtraade ; Hovedet indeholdes omtrent 5% Gange i Totalhing- 

 drn. J ste Straale i Iste Dorsal lang, omtrent af Hovedet s Længde. Tæn- 

 dirnc forholdsvis svage og ensartede. Amis ligger midt mrlhm Snudespidsen 

 og Bigijndelsen af Candetlen. Afstanélen fra Snmle spidsen til 2drn Dorsal 

 indeholdes 3,1 Gange i Totallængden. 



2 D. 09: A. 4.3—46; P. 22—2:i. 



Til Saminenlignincr kan vetlføjes foldende Maal af et Par I'lii- 

 trent lifre store Individer af de 1 Arter, beojre fra Musæet i Kjoben- 

 havn. 



' Onos ensis, (Reinh.) Is3") — 3(i. 



(Jvers. ls3:i— :!i). Kirl. D. Tid. Selsk. Xaturv.5Iath.Afli. f i Del, 

 p. CX, Kbh-i-n. 1837 (183:)— 3(i). 



Three barbels; length of head is to total length as 1 to o^/^. First 

 ray in 1st dorsal produced, its length equalling that of the head. Teeth 

 comparativelij feeble, and unifoiin. The vent placed midway between the 

 snont and the commencement of the caudal fn. Distance from point of 

 snoiit to 2nd dorsal is to total length as 1 to 3.7. 



2 D. 69; A. 43—46; P. 22—23. 



Foi- cimiparison are appended measurements of two individuals, 

 about equal in" size, of the two species — both specimens preserved in 

 the Zoological Museum in Copenhagen. 



