Volume II. February, l8gg. Number 4. 



ZOOLOGICAL BULLETIN. 



NOTES ON THE OCCIPITAL REGION OF THE 

 TROUT, TRUTTA FARIO. 



M. A. WILLCOX, Ph.D. 



Professor of Zoology in Welleslev College. 



About a year and a half ago I undertook an investigation 

 for tiie purpose of determining the number of segments in the 

 hinder part of the head in the Teleostei. Only when the work 

 was nearly complete did it come to my attention that Harrison, 

 in his paper entitled " Die Entwicklung der unpaaren und paari- 

 gen Flossen der Teleostier," had covered much of my ground. 

 Under these circumstances it seemed unwise to continue the 

 investigation. But as my results embody a few new points, I 

 give herewith a brief summary of them. 



The material was obtained from the Zurich fish breeding 

 station and consisted of eggs of the salmon, Sahno salar, and 

 the trout, Trutta fario. When they came into my hands, the 

 salmon eggs had already been developing twenty-nine days in 

 water of 10° Centigrade, and required twenty-eight days in 

 water of about 7°-8° ^ to hatch. The age of the trout eggs was 

 unknown, but I estimated them to be about four days older; 

 they required twenty-two days in water of about 7°-8° to hatch. 

 The material was preserved in an aqueous solution of corro- 

 sive sublimate, to which was added 20^0 of glacial acetic acid ; 

 it was then imbedded in paraffin, sectioned, and stained with 

 haemalum. The greater part of the work was done upon the 

 trout, the salmon being used only for comparison. 



1 The temperature was not determined at the time, so that this is merely an 

 approximate estimate based upon the observations of others. 



