Kai tlBRAPY |i? 



... I 



55 



In the small specimens of tlie common and longspined Cottus (1' , — 3'/., incbes) the 

 reproductive organs were very little doveloped. All the larger specimens of the c-ommon Cottus 

 liad spawned, but none of the lono-spined Cottus. Some of these bad ripe, runniiig spawn, most 

 bad well-developed, but not quite ripe sexual products. 



The investigatiou made of the cottids at Fænø shows, that the spawning 

 time for the common Cottus is over hefore the heginning of May, whilst the hmg-spined 

 Cottus is yet scarcely in full spawn. 



On May 12th 1902, the Director writes in the jourual that he had not 

 observed any spawned specimens of the loug-spined Cottus at Fænø up to that 

 date. The Biological Station left the Little Belt shortly afterwards, and the con- 

 dition of the cottids there was lost to sight. In the heginning of June (lOth) a 

 spawned female of the longspined species was found in Ise Fjord (Kattegat coast 

 of Sealland). 



D. 23—11—02. Off Kløverhage, 11 fm. (Great Belt). Small English trawl: 3 common 

 Cottus, one female and two males. The female was full of large-grained, light-red sjMivn, about 

 to be laid, the males had running milt. 



D. 5. & 8 — 12 — 02. Sjmim of common Coffits laid in tank, sent from Nyborg (Great 

 Belt) to Copenhagen. 



D. 4 — 1—03. Lyø in E., 20 fm. (western Baltic). Young-fish trawl on liottom; 1 female 

 of common Cottus, spawned. 



D. 5 — 1 — 03. Lyø in E., 13 — 11 fm. Young-fish h-awl on bottom: spawn of common 

 Cottus on roots of Laminaria saccharina and on Flustra. 



These observations from November 1902 to January 1903 show, that the 

 spawning time of the common Cottus falls in December. Ehrenbaum (1. c.) states, 

 that the common Cottus at Helgoland spawns in December and January. We also 

 have a single observation which iudicates, that the spawning time may extend 

 into Januarj': 



D. 14—1—04. Hestehoved in W. N. W., 4 miles, 11 fm. (true Baltic). Small English 

 trawl: 3 common Cottus, a female and two males; the female with wdl-developed spaicn. 



At the end of February and heginning of March 1903 we examined a 

 number of specimens of the common Cottus in the Great Belt and true Baltic. 

 They had all spawned. We also liad an opportunity on this occasion to observe 

 that some of the eggs which remained in the ovary of the spawned females con- 

 tained distinct embryos. 



D. 27—2—03. Hestehoved in N. W. to W., 4 miles, 11—12 fm. (true Baltic). Small 

 English trawl: 4 common Cottus, three male and one male. Ovaries of females almost empty, 

 some of the eggs remaining contained distinct embryos. 



The same condition was uoted by Nordqvist (Meddel. Societ. p. Fauna et 

 Flora fennic)* in females of the common Cottus on the Finnish coast. This can 

 ouly be explained on the supposition that pairing takes place. Ehrenbaum says 

 (1. cit. p. 123): Aber auch das Vorkommen der inneren Befruchtung als Abnormitat 

 muss vorlaufig als auf die nordlichste Ostsee beschritnkt angesehen werden.« The 

 preliminary boundary marked off by Ehrenbaum can now be extended, as we have 

 found, that fertilisation in the common Cottus also occurs at the Danish coasts of the 

 true Baltic. 



In earlier years the spawn of the two species of Cottus was occasionally 



* 26 Bd. 1900. 



