A. #. Verrill—Cephalopods of the North Ailantic. 123 
The advantage of using ferric ammonia citrate over ferric 
ammonia alum may be curiously shown as follows: 
lace ina small white porcelain basin about an ounce of a 
solution containing a few grains each of ferrous ammonia sul- 
phate and ferric ammonia sulphate acidulated with hydrochloric 
acid. Take about a milligramme of cyanide of potassium, or 
about as much dust of that substance as can be distinctly per- 
ceived and shake it into the basin. Each infinitesimal particle 
will produce a blue coloration as it touches the liquid, but on 
agitating, the blue (if the quantity of cyanide has been small 
enough) will disappear. If now the same experiment be re- 
peated with a solution of ferrous ammonia sulphate and ferric 
ammonia citrate, also acidulated, the blue color produced does 
not disappear on shaking, but presently settles or becomes more 
conspicuous, 
ART. XVI.—Brief Contributions to Zoology from the Museum of 
Yale College. No. .—The Gigantic Cephalopods of the 
North Atlantic ; by A. E. VERRILL. 
THE existence of several distinct species of gigantic ten- 
armed cephalopods, belonging to more than one genus 
sent two distinct species, both of which belong to the genus. 
Architeuthis of Steenstrup (or Megaloteuthis of Kent). The 
largest of these is represented only by the jaws of two speci- 
Mens, one of which (No. 1 my former article) was found 
floating at the Banks of Newfoundland, and the other (which 
* See arti i aes ee ican Naturalist, vol. i 
Jan, |e eters gong nym un Tipraaded Murray in a 
Naturalist, vol. viii, p. 120, Feb, 1874 
