20 Hjalmar Ostergren. [No. 9 



dispute the correctness of Såes' statements, and declare that his 

 Oligotrochus vitreus in every respect corresponds with M. brevis, 

 and think that it „will be sufficiently clear, that Oligotrochus vitreus 

 is identical with Myriotrochus (Chirodota) brevis.'- 



As M. brevis by later authors has rightly been considered 

 synonymous to M. rinhii, Oligotrochus vitreus has also had to share 

 this fate. 



The statements of Danielssen & Koren seem to me perfectly 

 inexplicable, if I am not to suppose, that they, when intending to 

 examine Oligotrochus vitreus, by an oversight got hold of spe- 

 cimens of Myriotrochus rinhii.^) I have myself caught M. (Oligotrochus) 

 vitreus in the Christiania Fiord, in the Aicinity of Bergen, and in 

 the Trondhjem Fiord. Besides, I have carefully examined numerous 

 specimens in the Zoological Museums in Stockholm, Christiania, 

 Trondhjem and Bergen (there one linds even some collected by 

 Danielssen himself). In this large material there is not a single 

 specimen, which shows any similarity to M. rinhii. All show in a 

 fully typical manner those qualities characteristic of M. vitreus. 

 The living specimens of both spedes are so dissimilar, that no nearer 

 relation between the two is suggested, except on a more careful 

 examination. 



That M. vitreus is a species perfectly distinct from M. riiikii, 

 I have been convinced, ever since I began to study the Scandinavian 

 Holothurians. I have also in my pamphlet on the system of the 

 Synaptidæ (1898 b) admitted both thése species. Still it was very 

 interesting to receive specimens of them from places which lie 

 so close to each other as Lyngen and Skraaven — the distance 

 is hardly more than 250 km. Even here, where their districts nearly 

 meet; the difference between the species is perfectly distinct. The 

 Norwegian specimens of M. rinhii in one respect certainly show a 

 similarity to M. vitreus, viz. the small number of spokes in the 

 Wheels. This shows that one cannot distinguish betwen the species 

 in question only by the number of the spokes. The same holds 

 good about two new species of Myriotrochus, now before me, al- 

 though they in some other respects widely differ. 



1) LuDwiG mentions (1892 p. 359) tliat he has examined a spechnen, which 

 was sent to him under the name of Oligotrochus vitreus^ hut that he didn't find 

 this specimen as a species different to Myriotrochus rinkii. It has probably 

 also been a specimen of the latter species, which had been sent to him under a 

 wrong name. 



