Crustacea. 41 



CRAYFISH CARD. 



Get a piece of stiff, smooth cardboard six inches by eight ; select 

 some dark color such as will make a good background for the 

 crayfish. With pencil make three fine lines lengthwise, one in the 

 middle, the others an inch from the middle. Make a cross at 

 the center of the middle line. Now dot all three lines at intervals 

 of half an inch, starting from the center. 



Separate the parts of a crayfish as in previous study. For this 

 the specimen should be slightly moist. If too dry, it will be brit- 

 tle. If too wet, it will stain the card. If the work is interrupted, 

 it is well to keep the parts on a damp paper or cloth, and covered 

 so they will not be scattered. The parts of a crayfish are so 

 compactly put together that it is impossible to see them all, while 

 in their natural place. One object of this work is to make a per- 

 manent preparation with the parts separated enough to show them 

 distinctly. The crayfish is supposed to be crawling along the 

 middle line of the card, and to have become dismembered and 

 strung out. The carapace is to be in the middle line, with its 

 hinder edge half an inch from the center of the card. The ab- 

 dominal rings are to follow this at intervals of half an inch. The 

 appendages are to be arranged along the side lines at intervals 

 of one half inch, with their bases at the side line, and extending at 

 a suitable angle forward. To support the carapace and abdominal 

 rings, make a cardboard bridge of the same material as the card. 

 This bridge should be just high enough to reach the under surface 

 of the arch of the carapace. The rings should be strung on this 

 bridge, and both the rings and the carapace sewed to the bridge at 

 the top, with a thread of such color as to be as inconspicuous as 

 possible. The ends of the bridge should be sewed to the card, 

 and the lower edges of both rings and carapace fastened so they 

 will not slip about. All needle holes through the card must be 

 made from above to avoid leaving a rough place. Determine 

 where each hole is needed, and pierce from the upper surface of 

 the card, whether the thread is to be passed through from above 



